Hello, i am seeing a bug in official Thunderbird 68.12.0 (64-bit) on Linux Manjaro.
Problem is like it is described in this bug report.
Please kindly if you have multiple mailboxes, try to go to View / Folders / Unified
and click parent “Inbox” item in the left side menu. The items disappear as i mouse over these and it shows error “TypeError: this._sort[aIndex] is undefined - DBViewWrapper.jsm” in Tools / Developer Tools / Error console.
If anyone want me to install different version or such, please let me know how to backup current one or how to install in parallel. I am having hundreds of thousands mails. But the unified Inbox just 6600.