[brazen1]

Sorry, I didn't notice your HEVC files are all 1080p and assumed they were all 2160p.

1) You have this rule:  <rule videoresolution="1080" player="MPC-BE"/>  (ALL 1080p RESOLUTION  titles are going to open with MPC-BE no matter what codec, file extension, file name, etc.)
and
2) You have this rule:  <rule filename=".*HEVC.*" player="PotPlayer"/>  (ALL titles with HEVC in the FILE NAME are going to open with PotPlayer no matter what codec, file extension, resolution, etc.) 

But there is a conflict.  All your HEVC (rule 2) files are ALSO 1080p (rule 1) files.  So, rule 1 wants to use MPC-BE and rule 2 wants to use PotPlayer.  That is a conflict.  You can't have it both ways.  We would want to 'nest' a further refinement to one of the two rules but afaik, you can only ADD to a nest and you need to EXCLUDE.  Something like:

<rule videoresolution="1080|[^…HEVC] player="MPC-BE"/>
or 
<rule videoresolution="1080" exclude videocodec="HEVC" player="MPC-BE"/>  but there is no meta-character KODI understands "[^…]" or an 'expression' "exclude" that would refine and eliminate afaik.  You can try playing with: <rule videoresolution="1080" videocodec="[^…HEVC]" player="MPC-BE"/>

Even if you replaced attribute rule filename with rule videocodec, there would still be a conflict between HEVC codec and 1080p resolution.

What happens if you use these rules:  (as I stated early on, two filename rules did not work for me long ago and not sure if that's changed but give it a try)

<rule filename=".*HDR10.*|.*HDR.*|.*hdr.*" player="KMPlayer"/>
<rule filename=".*1080.*" player="MPC-BE"/>
<rule videoresolution="480|576|720" player="MPC-HC"/>
<rule videocodec="HEVC" player="PotPlayer"/>

Make sure 1080 is in the file name for titles you want to open with MPC-BE.
Make sure 1080 is not in the file name for HEVC titles you want to open with PotPlayer.