[littlegandhi1199]

OK I think I figured it out!

The .edl files created by the Mute Profanity Plugin include an introductory and ending line that is nested with ###

###### This section is automatically maintained by the Mute Profanity plugin ######
00123.101    00125.458    1    #Muted
00311.228    00312.449    1    #Muted
00327.244    00328.244    1    #Muted
###### END Mute Profanity plugin section ######

If I remove these ## nested  lines (I need to remove from both the top and bottom)  the .edl file loads properly and everything works.  If there is even just a single # in those lines, the file won't work.

Strange that this wasn't a problem with all other Kodi versions.

Thanks for your help with this everyone!

2 follow up questions though:

1) Is this considered a "bug" that I should report / submit somewhere?  I suppose I can go through my several hundred .edl files and remove those lines manually, but if this could be fixed in kodi 18.6,  it may be nice!  I suspect this was an inadvertent result of 18.5's "Fixes to commercial skip (EDL) processing". 

2) There is still the annoying audio sync issue for a few seconds before and after every '1' (mute) where as with kodi 16.1 (and earlier builds) the mute worked perfectly.  Should I report this somewhere?

Thanks again for all your help!

Regarding #2 that there is still a sync issue.
Please take a look at my github issue request that I started
https://github.com/xbmc/xbmc/issues/17328

Can you comment over there to re-iterate what I said. This is my personal experience and I hope it's the same issue you're experiencing.
Let me know and echo my request if you can over there too!