Description
When a block with a non-full hitbox is placed adjacent to the basket's open side it becomes transparent.
Maybe it's an Optifine issue though?

Steps to reproduce:
Not sure what group of blocks causes this. I did some testing and think the screenshot should give you a good idea.

Expected behavior:
It should still be drawn ;)

Screenshots

Mod List:
forge-1.16.5-36.1.0-client.jar |Minecraft |minecraft |1.16.5 |DONE |NOSIGNATURE
FarmersDelight-1.16.5-0.4.3.jar |Farmer's Delight |farmersdelight |1.16.5-0.4.3 |DONE |NOSIGNATURE
decorative_blocks-1.16.4-1.7.2.jar |Decorative Blocks |decorative_blocks |1.7.2 |DONE |NOSIGNATURE
theoneprobe-1.16-3.1.4.jar |The One Probe |theoneprobe |1.16-3.1.4 |DONE |NOSIGNATURE
ToolBelt-1.16.5-1.16.0.jar |Tool Belt |toolbelt |1.16.0 |DONE |NOSIGNATURE
architectury-1.17.22-forge.jar |Architectury |architectury |1.17.22 |DONE |NOSIGNATURE
ftb-gui-library-1605.2.1.41-forge.jar |FTB GUI Library |ftbguilibrary |1605.2.1.41 |DONE |NOSIGNATURE
curiouselytra-forge-1.16.5-4.0.2.3.jar |Curious Elytra |curiouselytra |1.16.5-4.0.2.3 |DONE |NOSIGNATURE
moreoverlays-1.18.14-mc1.16.5.jar |More Overlays Updated |moreoverlays |1.18.14-mc1.16.5 |DONE |NOSIGNATURE
curiousshulkerboxes-forge-1.16.5-4.0.1.0.jar |Curious Shulker Boxes |curiousshulkerboxes |1.16.5-4.0.1.0 |DONE |NOSIGNATURE
jei-1.16.5-7.7.0.106.jar |Just Enough Items |jei |7.7.0.106 |DONE |NOSIGNATURE
OptiForge-MC1.16.5-0.5.5.jar |OptiForge |optiforge |0.5.5 |DONE |NOSIGNATURE
ftb-chunks-1605.2.3-build.75.jar |FTB Chunks |ftbchunks |1605.2.3-build.75 |DONE |NOSIGNATURE
caelus-forge-1.16.5-2.1.3.0.jar |Caelus API |caelus |1.16.5-2.1.3.0 |DONE |NOSIGNATURE
forge-1.16.5-36.1.0-universal.jar |Forge |forge |36.1.0 |DONE |22:af:21:d8:19:82:7f:93:94:fe:2b:ac:b7:e4:41:57:68:39:87:b1:a7:5c:c6:44:f9:25:74:21:14:f5:0d:90
curios-forge-1.16.5-4.0.5.2.jar |Curios API |curios |1.16.5-4.0.5.2 |DONE |NOSIGNATURE
create-mc1.16.5_v0.3.1c.jar |Create |create |mc1.16.5_v0.3.1c+151|DONE |NOSIGNATURE
ShulkerTooltip-1.9.8.jar |Shulker Tooltip |shulkertooltip |1.9.8 |DONE |NOSIGNATURE
journeymap-1.16.5-5.7.1.jar |Journeymap |journeymap |5.7.1 |DONE |NOSIGNATURE
polymorph-forge-1.16.5-0.25.jar |Polymorph |polymorph |1.16.5-0.25 |DONE |NOSIGNATURE
AutoRegLib-1.6-49.jar |AutoRegLib |autoreglib |1.6-49 |DONE |NOSIGNATURE
Quark-r2.4-312.jar |Quark |quark |r2.4-312 |DONE |NOSIGNATURE
createplus-1.16.4_v0.3.1.3.jar |Create Plus |createplus |1.16.4_v0.3.1.3 |DONE |NOSIGNATURE

Thank you for the project!

Yup, issue on my end. Thanks for opening it with so much information btw, I noticed it yesterday and didn't bother opening one myself. Helped me a ton! 😅
I fiddled with the render shape to get water to render correctly, but went overboard. Will be fixed for 0.5.

oh forgot: the blocks on top are (kinda) non-full but basket is drawing correctly!

Fixed on commit 50ef08f, should be out in a minor release pretty soon (assuming nothing new appears). 👍