Installing the WIP (8.5.7) version will not have any effect on the functionality of the release version. If you are getting the problem with v8.5.6, then it is something else on your system, or something else in your file that has changed.
Per your reports we have verified that there still can be an issue when using the Export 2d: PDF command -- but if you use the Print command instead, and print the PDF file using the Vector Output option, then you should get better results with this WIP version than with the release -- because we have added a number of improvements relative to printing.
There should not need to be a workaround to Printing PDF's because as far as we are aware, this is working normally for everyone else.
We did send a PDF and FML version of a file that is working fine for us. Did you have a chance to check the PDF we sent and do you see any problems with this? And if this is OK, if you open the FML and Print to PDF from there, does my file work properly for you -- or no?
Please let us know so we can help. (Feel free to email us directly again instead of posting here -- at least until we can come to some understanding or resolution -- or if you want to post to the forum, you should make a separate topic...)