Modpack version
1.67d

Can the issue be reproduced?
I can reproduce the issue on my world, I do not know if it is reproducible by others.

Issue
I am not sure if the issues are related, but

1. When viewing the items in an inventory, the inventory will suddenly clear and act like there no items in slots when I try to add/remove items. I have to exit the ui and open the inventory again to see the items. However, the items "disappear" again after a few seconds. This has been prominent with the Iron Chest Diamond Shulker Boxes and Thaumcraft Inscription Table's ink and paper slots. I do not have any issues with normal chests, shulker boxes, or diamond chests. It could affect more items than these, but this is what I have encountered.

2. After prolonged game time I appear to be unable to right click and use items such as loot boxes or eat food. I have tried with both an empty and filled off hand, but was had the same issue. The loot box would be "used" but I would receive no reward, then eventually the loot box would end up back in my inventory. The food would never finish the eating animation or use up the item.

Thanks for the report. I would like your latest.log so I can investigate the issues you're experiencing.

Are the inventories you're experiencing bug 1 on in the same chunk or area? If yes, are they near a Tinkers' Construct Smeltery?

latest.log

I logged in and checked, yes the inventories are in the same chunk, and it is the same chunk as a Tinker's Smeltery. The smeltery is above and my base is in a cave below. I brought one of the diamond shulker boxes out to a different chuck and the inventory is not disappearing.

You appear to be using outdated Java. This is often caused by Twitch defaulting to an older version than you have available. Follow these steps to update.

• Make sure you have the latest 64-bit Java installed
  https://www.java.com/en/download/manual.jsp Windows Offline (64-bit) is the one you need
• Go to the Twitch Minecraft settings
• Add -version:1.8+ to the Additional Arguments

Please see if that resolves issue #2

Java Downloads for All Operating Systems

Java manual download page. Get the latest version of the Java Runtime Environment (JRE) for Windows, Mac, Solaris, and Linux.

Cool, that particular bug should be fixed in the next update of the pack, it was a mod interaction.

This issue has been automatically closed because there has been no response to our request for more information from the original author. With only the information that is currently in the issue, we don't have enough information to take action. Please reach out if you have or find the answers we need so that we can investigate further.