Corrupted Flash display with Firefox 32-bit running on Linux Mint 64-bit

Title says it all: Corrupted Flash display with Firefox 32-bit running on Linux Mint Xfce 64-bit

...while Flash displays correctly with Chromium 32-bit running on same Linux Mint Xfce 64-bit.

Linux Mint 18.2 Xfce (64-bit)

uname -a :

Linux PC 4.8.0-53-generic #56~16.04.1-Ubuntu SMP Tue May 16 01:18:56 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

Firefox version :

55.0.2 (32-bit)

Mozilla Firefox for Linux Mint

mint - 1.0

Flash version :

27.0.0.130 (32-bit)

Flash test site : Flash Player Help

Screen shot with corruption :

Firefox Plugin page on Flash :

Thanks in advance for anything you can provide toward fixing this issue.