Greetings,
I was looking forward to installing your mod to my RLCract server/client, and when i went to test out the features to check for any bugs or incompatibilities i had forgotten that one of the mods thats included in the RLCraft modpack used the same key binds, that mod is called "Carry On" and is created by Tschipp and Purplicious_Cow_, you can find its curse forge page here https://www.curseforge.com/minecraft/mc-mods/carry-on
the issue is that when i went to use the CarryOn mod to pick up the Traveler's Backpack i found that it had no texture when held that way, below i'll provide a screenshot of what it looks like when carrying other things with the Carry On mod and what it looks like with the Traveler's Backpack