Unable to open a vault

I created two vaults on my iMac using latest os version and place files in them… Initially, both work fine., maybe for 24 hrs. Then, when clicking on either vault, I get message “Cryptomator is unable to locate a vault by this path”. I can recapture vault access through master key, but after a short time, the same problem occurs. This happens repeatedly and I have no access to my files. Please advise me what I am doing wrong and how to fix this. Thanks. L

Do you have “online-only” files/files-on-demand/virtual files enabled? If so, please set the vault storage folder to be always available offline.