Hey there @rich841 , thanks for coming back to us about this, and my sincerest apologies for the delay in responding. I appreciate you answering our questions!
Just to be clear, the save files should be in '%userprofile%\Documents\Anno 1800\accounts' - is this where you've found your save files to be stored?
Please see our troubleshooting guide. In particular from that guide, please make sure you've updated your operating system fully, you've verified the game files, and you are running the game without any modifications and no background programs or processes, and with admin rights.
If the issue persists after those steps, please let me know - I'll have some further steps we can try in that case!