What's Expected To Happen:

Backside Block-face Culling will still apply to transparent block, even when the player has an empty hand.

What Actually Happens:

Block-face culling for all air-exposed faces gets interrupted while the first person hand model is rendered on screen.

Examples:

Screenshot of Proper Rendering when holding any item:

Screenshot of broken rendering when first person hand model is visible:

Screenshot showing that third-person rendering is functioning as expected:

This affects almost all Glass Blocks, Plants/Crops, and Leaf Blocks.

Important Notes:

While I am using a slim arm model in the screenshots, this does not seem necessary to trigger the bug. Using a thick arm model still interrupts air-exposed culling.

Nothing get written to the console while the hand is being rendered.

I am certain it's between Ears and Angelica as disabling either one fixes the issue (Though disabling Angelica results in a very laggy game, and disabling ears results in no Ears and a broken skin).

Turning off Translucency Sorting in Angelica seems to fix this issue without needing to remove Angelica altogether.

This is strange and i'm not sure what would cause this — I guess some kind of state leak, but I'm not sure what would leak state in the first-person arm renderer and not the player renderer. Maybe the blend state? Ears adds a special kind of translucency-capable entity cuboid for compatibility with 1.9 translucent skins. It's also possible the cull state gets changed? I don't remember — 1.7 is a really weird Ears port.

Ears is also completely broken with Smart Moving in 1.7.

Disabling "GL State Cache" from Angelica's Performance settings fixes the issue.

Still cannot replicate the original issue here. @TimeBender25 can you confirm if the issue still persists on GTNH 2.7.2?

We're able to confirm that it it functions exactly as you reported, our original report was made on GTNH 2.6.1 with an early release of Angelica (and we're kicking ourselves for not labeling the angelica version).

The backside culling works perfect fine and as expected in-world, and even in-inventory. But not in Chests Specifically. Though the Type of chest does not seem to matter, as all the Iron Chest tiers also cause the flickering of the item model.

Screenshot of behavior with an empty hand, culling acting as expected:

Screenshot of Culling with empty hand in a Chest-type inventory:

Placing any item in the selected hotbar slot returns the behavior to normal:

This is with Angelica 1.0.0-beta28, GTNH version 2.7.2, and Ears version 1.4.5_01.

This also affects block rendering in the inventory.

(Look at the frame blocks, compare with below:)

Actually, we can't seem to replicate the exact issue on Angelica 1.0.0-beta28- partially transparent blocks placed in the world (also tested wheat crops exactly) doesn't seem to break anymore...?

Sidenote, the issue as observed in the inventory doesn't happen in the main inventory menu, but it does happen in chests. Vanilla ones seem to work, no idea if the bug is actually related.

EDIT: Seems to be a separate issue and seems to be on Angelica's side: GTNewHorizons/Angelica#615 (comment)

Still cannot replicate the original issue here. @TimeBender25 can you confirm if the issue still persists on GTNH 2.7.2?