I have just moved over to PD 18 - 365.
Today I was just playing with my camera to see how the colour grading of PD18 compared with the different movie settings produced 'In-camera'.

I noticed some very strange behaviour and I wonder if anyone else has found this problem, or someone could come up with a possible reason/cure.

I was using a Fuji X-T3. This camera produces 'MOV' files. They load into PD18 no problem.

(Incidentally, PowerDVD will NOT play these 'Off-camera' files without stuttering, even when reading off a fast ssd - Though the standard windows player is totally fine with them - But that's not the issue here...)

I shot 3 clips, one in 'Standard', one in 'Eterna' and a final clip in HLG. This last clip caused the problems...
It was recorded 4K, 25fps, HLG, 'Long GOP', h265, 200mbps, 10bit, 4:2:0

I put the three clips together in the time-line. They played fine. All smooth.
I colour graded the HLG clip and 'Produced' all three together as a short movie.
During the production, I noticed a 'Freeze' when the final clip was reached, for say 7 seconds, then it blasted on to the end of production...

I played this in PowerDVD (Converted files play smoothly) and watched. The first 2 clips produced correctly, but the HLG colour graded clip was black... Sound, but no picture.

I tried again, this time JUST the HLG clip.
If I 'Produced' it with no colour grading, then it was visible and played... albeit looking washed out as un-graded HLG isn't great.
I tried three different LUTs on this clip and each time there was a delay in the production at the start, followed by a very fast render producing nothing but a black screen with sound.

I then tried one of the other clips - I chose 'Standard'... Recorded 4K, 25 fps, Long GOP, 200 mbps, 10 bit, 4:2:0
I ran this through 'Production' three times - each with one of the LUTs I'd tried on the HLG clip...
All three produced correctly ! - Though this time with far too vivid colours as I was applying a LUT to an already 'In-camera' graded video.

So - It's not the LUT or its use totally at fault, as this can be applied and 'Produced' - Where it's not required !
(At least I know I can use 'Gentle' LUTs to change the look of videos without a problem.)
The HLG clip could be 'Produced' as long as no LUT was applied - Which makes it sort of useless...
It seems to be the COMBINATION of using a LUT and an HLG file... ?
And when in PD18, the viewer had no problem playing the colour graded HLG...

Anyone any idea what's going on ?

I will see if I can have another play tomorrow and will also record in F-Log and see if these files will accept a LUT in PD18.

Maybe something about the Fuji X-T3 HLG format that PD18 production doesn't like ?

I wasn't using any shadow files or anything other than off-camera.
I had transfered the recorded MOV files from the sd card to my internal 'Video working' ssd.
The program itself is held on another ssd - where windows and all other programs live.
I was 'Producing' onto an 'old school' disc-based hard drive. It can write faster than PD18 can produce the video so never an issue before...

PC is a water-cooled Ryzen 2700 over-clocked to 4GHz, nVidia 1070 8Gb Graphics (Correctly identified by PD), 32 GB RAM.

Any suggestions welcome !

Gerry