Flash graphics corrupt on Firefox on Kubuntu (with AMD graphics)

[pbhj]

I'm using Firefox 48.0+build2-0ubuntu0.16.04.1 on Kubuntu 16.04 with AMDGPU-PRO graphics drivers (I mention that as it may be the reason for the issue, the system runs AMD's A8-7600 which is listed as a Radeon R7 in KDE's kinfocentre).

freshplayerplugin is installed and I have both of the following files [which are identical, according to md5]:

/opt/google/chrome/PepperFlash/libpepflashplayer.so
/usr/lib/pepperflashplugin-nonfree/libpepflashplayer.so

Chrome/Chromium report the same flashplugin version details, these from Chromium:
51.0.2704.79 (Ubuntu 16.04), [...] Flash plugin 22.0.0.209 /usr/lib/pepperflashplugin-nonfree/libpepflashplayer.so
Firefox confirms the same version details in the about:addons screen.

All Flash elements on all pages visited are corrupted, they appear to show variously parts of the correct output, parts of config information, parts of other application windows (screenshots attached).

[If there's anything I, as an experienced user, can do to "fix" this then I'm happy to work on it, but I'll be away for about 10days from tomorrow].

Examples of flash element corruption:

Note that other facets of the plugin, UVC camera support also appear to be problematic, I can't access image capture pages that I've used in the past.

[i-rinat]

Does this happen on all pages with Flash?

Try https://i-rinat.github.io/flash-test-cases/PartialTransparency/index.html, please. There should be three instances of Flash movies, one white oval in a transparent box with thin black border, and other two just white boxes. With text in all three instances. (There are different modes for embedding Flash on pages, some of them may work, but some could be broken. This should help to identify which are.)

[DWSampson]

I have experienced that before, it's a Graphic Driver issue, you may have the wrong propriety driver installed, you may find useful information on this site: http://askubuntu.com/questions/778205/16-04-radeon-r7-m260-errors or here http://support.amd.com/en-us/download