I’ve not experienced this myself although I don’t use AxCrypt on a network share.
When you say “AxCrypt decrypts all the files in this secured folder” I assume that you mean the icons change from the green padlock to their original icon?
It’s not clear whether you’re describing a ‘permanent’ decryption (where you’ll need to manually re-encrypt) or a temporary decryption where you can work with the files by just double clicking on them. If it’s the second scenarion (decrypt when you click on them) this is an intended behaviour.
Do the files in the original folder encrypt themselves once you’ve logged out? Does the error reproduce thereafter?
Here’s some background reading on network shares; because of how Windows works it’s extremely difficult to properly: