On two occasions I've logged into the game to discover the belt has disappeared, taking its contents with it.

Wat ... o_O
I don't know how that could even happen.
Was the tool belt in the internal slot from toolbelt? curios? or where?

Hmm, that's bad.
What minecraft version? 1.17.1?

I think I'm losing it when I log out. I logged in and it's gone again. I went to grab one of my tools, pressed r to bring up the radial but nothing appeared. So I pressed v and the belt slot shows empty.

Yes

I'll take a look.

I replaced it and relogged to try to trigger it and still have it. I'll keep a closer eye on it and when it happens again I'll send you the file.

I'm also using the following:
appleskin
aquaculture
dynamiclights
fastleafdecay
xaeros minimap
xaeros worldmap

I can't make it happen. The belt is still there when I log back in.
Can you send me the latest.log file from your game?
Also, are there other mods in your installation?

Hello. I had happened again. How would you like me to send you the latest log?

I noticed this in it a couple of times:

[21:04:16] [Render thread/INFO]: Skipping loading recipe toolbelt:pouch_upgrade_5_via_sewing as it's serializer returned null
[21:04:16] [Render thread/INFO]: Skipping loading recipe toolbelt:pouch_upgrade_1_via_sewing as it's serializer returned null
[21:04:16] [Render thread/INFO]: Skipping loading recipe toolbelt:pouch_upgrade_7_via_sewing as it's serializer returned null
[21:04:16] [Render thread/INFO]: Skipping loading recipe toolbelt:pouch_upgrade_2_via_sewing as it's serializer returned null
[21:04:16] [Render thread/INFO]: Skipping loading recipe toolbelt:pouch_upgrade_4_via_sewing as it's serializer returned null
[21:04:16] [Render thread/INFO]: Skipping loading recipe toolbelt:belt_via_sewing as it's serializer returned null
[21:04:16] [Render thread/INFO]: Skipping loading recipe toolbelt:pouch_upgrade_6_via_sewing as it's serializer returned null
[21:04:16] [Render thread/INFO]: Skipping loading recipe toolbelt:pouch_via_sewing as it's serializer returned null
[21:04:16] [Render thread/INFO]: Skipping loading recipe toolbelt:pouch_upgrade_3_via_sewing as it's serializer returned null
[21:04:16] [Render thread/INFO]: Loaded 7 recipes
[21:04:18] [Render thread/INFO]: Loaded 1211 advancements
[21:04:18] [Render thread/WARN]: Missing data pack mod:minecraft
[21:04:18] [Render thread/WARN]: Ambiguity between arguments [teleport, location] and [teleport, destination] with inputs: [0.1 -0.5 .9, 0 0 0]
[21:04:18] [Render thread/WARN]: Ambiguity between arguments [teleport, location] and [teleport, targets] with inputs: [0.1 -0.5 .9, 0 0 0]
[21:04:18] [Render thread/WARN]: Ambiguity between arguments [teleport, destination] and [teleport, targets] with inputs: [Player, 0123, @e, dd12be42-52a9-4a91-a8a1-11c01849e498]
[21:04:18] [Render thread/WARN]: Ambiguity between arguments [teleport, targets] and [teleport, destination] with inputs: [Player, 0123, dd12be42-52a9-4a91-a8a1-11c01849e498]
[21:04:18] [Render thread/WARN]: Ambiguity between arguments [teleport, targets, location] and [teleport, targets, destination] with inputs: [0.1 -0.5 .9, 0 0 0]
[21:04:18] [Render thread/INFO]: Reloading ResourceManager: Default, dynamiclights-1.17.1.1.jar, forge-1.17.1-37.0.27-universal.jar, Aquaculture-1.17.1-2.2.1.jar, ToolBelt-1.17.1-1.17.3.jar, FastLeafDecay-26.jar, Xaeros_Minimap_21.15.1_Forge_1.17.1.jar, appleskin-forge-mc1.17.1-2.1.0.jar, XaerosWorldMap_1.16.1_Forge_1.17.1.jar, rusticregen-1.17.1-1.3.0-RELEASE.jar

Hi sorry was sleeping when you replied. If you could upload the latest.log to https://gist.github.com/ and link the gist here, that'd be great.
The snippet you copied just shows Sewing Kit isn't present which is fine. "Skipping loading " messages are harmless.

Here, had to put it inside a zip so github would allow me to upload.

EDIT: Sorry that will crash, my bad! NEw upload soon.

It should print extra info in the latest.log or debug.log.

Here this should work and log the messages as intended...

ToolBelt-1.17.1-1.17.3.2.zip

Uhm you didn't have to generate any script thing, just code the URL of the page after creating it.
That is, https://gist.github.com/Amalicious/bb4e17baf34394d1b24dfb40bdc9f46c

I'm not sure if I did this correctly. I'm not very well versed with all this; I made an account to tell you about the tool belt issue. Let me know if you need something else :)

Oh I dunno, I created the thing and there was a clipboard icon to copy it and that's what I pasted :)

I see that you died at one point, but you didn't just close the game afterward.
Would you be willing to test a special debug version of the mod?
I'll upload here a build with more information printed to the logs that you'd normally see.

Sure, why not.

Oh? I'll take a look as soon as I get home!

Hey! I figured out what's doing it. Going through the nether portal is breaking it.

https://gist.github.com/Amalicious/e7e1d6a015caa03282b6338142cf2b54

Hmm, I have spoken with some other devs, and we think the issue is a problem with capabilities that was fixed in forge 37.0.29.
You should update to at least 29 and see if it stops happening. You should update to latest, though since it has other fixes.

I'll try it and let you know :)

I updated to most recent. Went to the nether and back, still have my tool belt! Thank you :)