I use the same software versions here. My WSPR settings don't change and stay with DIGU. Mode changes most often depend on your radio settings. I use HamRadio DeLuxe and MiniDeluxe as my server. Try changing the radio settings in WSJT-X and see, wheter the mode also changes with WSPR.
I changed from Kenwood TS2000 to Flex 6xxx and now I error out with "HAMLib error: IO error....." I seems to stay in DIGU so I think you gave me the first positive lead. Do you have any additional information that could help