Text in a QTreeView/QTreeWidget that is horizontally center-jusitifed or right-justified produces displays errors when the text becomes elided. This makes the text increasingly unreadable as the column shrinks and more text is elided, eventually reaching the point to no next being displayed.
The expected result is that the left side of the text remains visible no matter the size of the column.
This is a regression that occurred in 5.12.0 and has not yet been fixed in 5.12.1. This has somehow been fixed in the 5.13.0 alpha.
Hopefully that fix can be pulled into 5.12.x given its LTS status.