Issue with dragging around tabs, file display not responsive

Following happens, when i load some older tab group: both sides show the tabs, as expected, but the left display shows a bread crumbs location field, while the right side does not, even though both sides are using the details mode. When i start dragging around tabs at the right side (might be the same for the left side), some of the existing tabs shows up as a duplicate. From then on, there is no more reaction whatsoever in that file display.

Dragging or activating tabs isn't possible, nor clicking any item in the list. The other file display keeps operational. What i also saw happing with the frozen file display, that the "frozen" side suddenly (maybe after a task change?) shows up completely blank. That is, no background/backdrop is visible, no folders, no tabs, & no bread crumbs location field, but the top toolbar, containing a menu, plus the drives tool bars at the right, stays visible. It also still works, but only for the remaining side.

I have to correct myself. The issue starts, if that duplicate folders shows up, & i try to close it, using a right click on that folder, "close tab". Seems not to happen with the left side, though.

I found, comparing the tabs actually loaded, to those in the preferences previews, that one of the tabs on the right side is different from what the preview shows. Once i had that one removed, & resaved both sides, the whole issue seems to be gone.