HDR tone mapping on multiple displays

[R_C__]

Hi all.

Attempting to play an HDR10+ H.265 stream on Mac Catalina with VLC 3.0.11.1

I have three screens attached to my 16" MBP. These are attached via native thunderbolt adapters (that don't use displayLink).
All three monitors are standard SDR displays, so I need the image tone mapped.

VLC appears to tone map quite well on the primary screen, but when moved to either of the other two it renders as the flat, "ungraded" video.
Is this by design or a limitation? The Plex player app tone maps the content on the fly very well regardless of screen (and without needing to transcode), hopefully it is just something simple I am missing or a bug?

I tried altering which display is the "main" one in the display settings to no avail. Now the centre screen (which displays correctly) is an Eizo (CG241W) vs the other two which are standard Dells. The standard Dells however hold up not to badly vs the Eizo in all other apps and the quality difference wouldn't explain what I am seeing. Any help appreciated.

Many thanks in advance,
Richard.