Here is the Scenario:
These are customized banners that have been renamed. And I have a lot of different ones.
I am using barrels in this situation. I go to drop some off in a barrel only to have them drop to the ground when I exit the barrel screen. I have not tested this with chest, but it seems to happen more when I have a lot of different ones in my inventory or the barrel has a lot. I have logged out and back in several times and the issue persists. Sometimes they don't like to stack and sometimes they stick in my inventory too. It's hard to show in an image but I attached my F3 and a screenshot to give you an idea of how many banners I have.
Thank you for your report!
However, this report is Invalid.
The server you are experiencing this issue on is heavily modified by software such as Spigot, Paper or similar.
If you can reproduce the issue in a vanilla server environment, please create a new ticket - this is a bug tracker for the game, and not a support website.
Any non-standard server issues needs to be taken up with the appropriate third party development team, not Mojang Studios or the Bugtracker.
Any plugin issues need to be addressed to the creator of the plugin.
If you have problems on large servers, such as The Hive and Hypixel, please contact them first as they run even more extensively modified server software.
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