DGDecodeNV Crashes when upscaling to 1080p

[VideoFanatic]

I'm having some bother upscaling a 576i h264 Elgato Game Capture HD video to 1080p 50fps. I'm upscaling to minimize quality loss by YouTube re-encoding it. This is my script

setmtmode(5,6)
DGSource("Video.dgi")
setmtmode(2)
AssumeTFF() 
Tweak(Bright=20, Sat=0.7, Cont=1.0, Hue=0.0, Coring=False)
QTGMC(Preset="Super Fast")
MergeChroma(awarpsharp2(depth=25))
McTemporalDenoise(settings="low", interlaced=false)
Crop(60,0,-62,-4) 
AddBorders(60,0,62,0, $000000)
nnedi3_rpow2(2, cshift="Spline36Resize", fwidth=1920, fheight=1080)

I'm using DGIndexNV to index the video. I'm encoding to CRF 16 1080p 50fps. The video will start encoding fine but after several minutes it will start encoding more slowly until after several minutes it goes down to 1fps. Then it crashes. However if I were to add a re-interlacing line to the end of the script then it does NOT crash and the encoding speed is consistent! Why does it only crash when encoding to progressive?

Instead I thought I would encode to lossless 576i with x264. That worked fine. However when I then try to upscale the lossless video to 1080p with this script, the video instantly crashes:

Yadif(mode=1, order=1)
nnedi3_rpow2(2, cshift="Spline36Resize", fwidth=1920, fheight=1080)

The lossless video is High 4:4:4 Predictive@L3.0 and has 4:2:0 Chroma. I assume DGIndexNV doesn't support 4:4:4 which is why it crashes but why does DGDecodeNV crash with the script at the start of this thread when DGIndex NV supports High@L3.0 videos as I've encoded them many times before.

Also when encoding to lossless, can I choose a lower profile than 4:4:4 such as High Profile?

[manono]

Does it still crash when you turn off multi-threading?

[VideoFanatic]

Never mind. Looks like it was due to MTMaskTools2.dll. I'm using a patched version and that's solved the problem. However I can only run in non-MT as MT crashes.