I set up my icons manually as I too have found the regular methods to be flaky.
Here is something that you could try based upon my UK Freeview setup.
Download the following vdr icons and meta files and extract them.
SSH into your box, moving existing picons and meta files from the following locations to your PC for restoration if this process doesn’t work.
Then copy the extracted picons and meta files to these 2 locations respectively.
Reboot and test.
You may find one or two channels require manual alterations but in the main it should work.
The meta files contain the details of the location of each picon file.
There is nothing to lose as you can simply restore your backed up files.