After upgrade to 5.5 attempt to open one of the service plans/store screens fails with an error:
Communication Failure: Error in method invocation.
In PBA 5.4 the CATEGORY_LIST_ID parameter was editable and it was possible to have a space sign there, in PBA 5.5 categories are added by the button, values in the database are validated differently. The issue is reported as a bug with id PBA-47743.
The way to resolve includes changes in the database, please contact Parallels Technical Support for assistance.