Sorry, but, what new version are you talking about?

Your Firefox identified itself as Developer Edition 32-bit, AKA Firefox 52 Aurora.

It's possible that Flash is the ONLY plugin that will run in Firefox 52 and later. I think that was the plan several months ago. However, I haven't investigated it in detail.

Yes, that is happening in Firefox 52:

https://www.fxsitecompat.com/en-CA/docs/2016/plug-in-support-has-been-dropped-other-than-flash/

In the Win64 Firefox Release only the 64-bit Flash Player and Silverlight Plugins were white listed to run. If you want to use other Plugins in Firefox such as Java then you need 32-bit Firefox and 32-bit Plugins.

That is until the Plugin support is changed as mentioned above.

The Firefox 52.0a2 you are Testing is not a new version but a build on one of the four main development channels. The Aurora and Nightly gets checkins almost everyday so they get a update each of those days. This can sometimes mean issues until the checkins finished, fixed, or reverted.

Release < Beta (b#), Aurora (developer edition) (a2) < Nightly (a1)