SUMMARY
I installed ddrescueview which does not associate with any filetype, but I regularly want to view log files with it. So I right-clicked a ".log" file, selected Open with → Other Application and entered /usr/bin/ddrescueview.
The dialog remembered this input, so when I open it again, it shows an entry at the top of the drop down. But selecting that entry does nothing. I have to select another entry first and then re-select the first entry. Only then is the central area updated and I can click the Open button.

Additional question: how can this dropdown be (selectively) cleaned up from previous entries, short of editing a config file?

STEPS TO REPRODUCE
1. Select a file in Dolphin, right-click, select Open With → Other Application
2. The dialog opens. Select the first entry from the dropdown. (If there is none, enter something to open the file with it for the first time).

OBSERVED RESULT
Nothing happens in the dialog.

EXPECTED RESULT
The selection should update the dialog so I can open the file with my selected application.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.9.0
Qt Version: 6.8.1
Kernel Version: 6.12.4-arch1-1 (64-bit)