Bug #18 was either never fully fixed
it has returned
rubidium version 0.5.2a

tinkers construct version- 3.5.1.31

Found that upon world launch if i hit f3 and t to reload textures its fixed
so likely a texture loading issue

Can confirm.

I've been experiencing this issue as well, in the modpack All the Mods 7. It's only occurring on tools that are added by datapacks / kubejs.

Tools with vanilla parts are rendered correctly in-hand, as well as in JEI. The cleaver below is deepslate and spruce wood:

However, tools with mod-added parts show up as white. Here the parts are unobtainium and vibranium, added the the mod allthemodium.

Note: Reloading textures once the pack has loaded has no effect.

Here are the versions:
Modpack: 0.4.25
Rubidium: 0.5.3
RubIE: 0.0
Tinkers: 3.5.1.31
Mantle: 1.9.27
Oculus: 1.2.5

Happy to help troubleshoot or investigate.

Yeah, i have the same problem...

Dunno about you but to me sometimes it happens sometimes it doesn't

The same problem here, Rubidium 5.3.0a and Tinkers 3.5.1.31

There is a workaround for this:

Find the "rubidium-mixins.properties" config file, then add "mixin.features.item=false" (without the quotes) underneath the notice.

From here:
https://mineyourmind.net/forum/threads/how-to-fix-broken-t-construct-item-textures.32974/

@Cannoner's workaround worked for me. I'd say this can be closed.

This should not be closed for that reason, the workaround is simply disabling part of the mod. That is like saying this can be closed because removing Rubidium fixes it.

Having the same issue on my pack, Evulgations.