Java Webstart Suddenly only opens in Windows on Parallels

I teach online using Blackboard Collaborate. The online classroom runs via Java Webstart and is activated by taking a link in a browser.

All has been fine until mid day on Saturday after I installed a Firefox update (might be coincidental). Now instead of the Mac-side Firefox opening up Collaborate the Window's side Firefox automatically kicks in and the Windows version of Collaborate opens instead of the Mac version like it has always been using.

My troubleshooting so far -
Firefox and Safari are both showing Mac Firefox as my default broswer. I click the link from the Mac Forefox and it downloads the jnlp file as usual but the jnlp file turns up every time in the downloads folder as the Windows (guest operating system through Parallels) as the default associated with it and it launches to Windows version of Collaborate.

I have tried right clicking on the jnlp file in my downloads folder and telling Mac to always open with Mac Firefox but as soon as I click to launch it jnlp reverts back to Windows version. I even tried the right click and just had it open that one instance with the Mac Firefox which then launches huge numbers of blank Mac Firefox windows that continue launching until I delete the original jnlp file.

I am wanting to try to set the jnlp file to open directly with Java webstart, but it isn't in the list of apps that I can associate to it.

Any ideas on what can fix this issue? I need the online classroom to open on the host Mac side because of some apps that I need to use are on that side. The Windows side cannot see them like the Mac side can.

OK, I have a manual solution in place.

After the Firefox update, Forefox was listed as the default app to open the jnlp file. I checked with other Mac users that use the online classroom and their file association is showing directly as Java webstart on the Mac side. I can manually tell Mac to open the jnlp instance with Javawebstart and get in.

Now to just figure out how to get it to always open with the webstart. It is listed in the recommended section when I right click on the jnlp. If I click other, it isn't on the list, so there isn't a way to tell Mac to always open with it. Anyone know how to make the association stick?