SUMMARY
Project files are not saved

STEPS TO REPRODUCE
1. Start a new data or audio cd project
2. Add some files
3. Select File > Save As...
4. Change directory path to use Documents directory and change name from "Audio CD" to something else
5. Click Save button
6. Close project and try to reopen from list of recent projects

OBSERVED RESULT
After step 5, no errors were reported. Project name shown as name picked in step 4. After step 6, it reports can't open file. This is because the project file does not exist.

EXPECTED RESULT
I expect to see the project file saved in the location specified or an error reported.

SOFTWARE/OS VERSIONS
Windows: 
MacOS: 
Linux/KDE Plasma: Mageia 6
(available in About System)
KDE Plasma Version: ?
KDE Frameworks Version: 5.42.0
Qt Version: 5.9.4 (built against 5.9.3)

ADDITIONAL INFORMATION
K3b version is actually 17.12.2, but there is not a dropdown selection for that version.
Some searching found some files that were saved, for example:
   .local/share/RecentDocuments/Jim+Dave-121218_pt1.k3b.desktop
with contents:
   [Desktop Entry]
   Icon=application-x-k3b
   Name=Jim+Dave-121218_pt1.k3b
   Type=Link
   URL[$e]=file:$HOME/Documents/Jim+Dave-121218_pt1.k3b
   X-KDE-LastOpenedWith=k3b

but the file $HOME/Documents/Jim+Dave-121218_pt1.k3b does not exist.

Now, I've searched on Google and here and found only a couple references to the same problem, but no solution. I know it can't be wide-spread or there would be a lot more discussion about it, yet I can't find anything wrong with what I'm doing.