MMOItems 6.10.1 - Custom model data bug/suggestion for 1.20.4

Good afternoon, I wanted to report the following bug: Using the mmoitems 6.10.1 dev version, when trying to use a custom model data, it doesn't seem to work. I've tried using older methods from 6.10, such as using cmd, but these no longer seem to work.

I'm currently using version 1.20.4 and was wondering if it's possible to add or fix this feature for this version in future versions of the plugin.