With TinkersLevellingAddon-1.16.5-1.1.1.jar / TConstruct-1.16.5-3.3.4.335.jar the example datapack for changing the 'Improvable' modifier does not work.

The reason seems to be that an incorrect pack.mcmeta was used (format 6 instead of 9).

After replacing pack.mcmeta with the one from TinkersLevellingAddon-1.16.5-1.1.1.jar everything works as intended.

I removed the entire "slots" entry for that - just like in the example.

Hi, I've been having the same issue as you. I did what you suggested in your answer and it doesn't seem to work. Here is my code incase I need to be humbled and know what I did wrong with it.

I am trying to make it use no slots/ability slot. Forgot to mention above

Hi, I've been having the same issue as you. I did what you suggested in your answer and it doesn't seem to work. Here is my code incase I need to be humbled and know what I did wrong with it.

I removed the entire "slots" entry for that - just like in the example.

Strange I thought I did it during one run but that didn't work at all. Must've goofed it up a little. Thank you so much! Got it working now

Hey,
I just re-tested all example datapacks and they are working fine. Make sure you are using the correct version for each of MC version as there are some differences.

The reason seems to be that an incorrect pack.mcmeta was used (format 6 instead of 9).

For 1.16.5 the correct format is 6.
9 is for 1.18.2.
You can check proper pack format on the MC wiki.

If you want to customize the recepe it's best to check on Tinkers' Github wiki or their new documentation page.