While composing screen shot for thread => Sync tabs had to click several times on "+" to open a new tab, sometimes a click highlighted box around "+" that also happened after dragging a commentary to vertically split a panel:

that needed a click on the "+" to change appearance (which did not open a new tab):

Mouse hover over "+" changes appearance of "+" that can be clicked to open a new tab:

Wonder if mouse over changes are related to threads => Entering a passage list is frustrating and => minor but annoying Mac bug
Edit: attaching diagnostic log files, noticed Logos4Error.log has some entries.
4452.23-Index.zip
On a Logos 4.5a installation on Mac, noticed a darker "+" in a panel while mouse was several panels away opening a New Tab using "+", but currently not know how to repeat.
Keep Smiling [:)]