I finally managed to get some time on the PC. I killed the wineserver (wineserver -k) and followed the procedure outlined by Matej on 2026-03-06 in the thread entitled ‘PrePoMax fails under Linux since 2.4.4’
I am happy to report that version 2.5.1 dev now works! The only issue is that the prefix characters have not disappeared, unlike Matej’s.