SOAPUI 5.8.0 breaking charset of project file

Since I upgraded to version 5.8.0 on my new WIndows 11 notebook, I experience a weird behaviour. I have rather large project file which imported many endpoints from WSDLs. So far everything worked fine, except in this version, when I save and close the project and SOAPUI and then restart, some characters in the project file are "broken" and SOAPUI refuses to load the project.

This happened multiple times in a row now. I corrected the file, made a copy, then after saving the original file was corrupted, but the copy was loaded without problems. 

RIght now I am considering revrting to the 5.7.2 version, which did not do this.