Xnview doesn't display video clips colours

[hugojans]

I reported this bug wrongly in the MP General Support section, sorry for that, it should be mentioned here: an MP4 short video is shown in only grayscale, with sound, in XnView Classic V2.51.1 (6 Sep 2022). MP4 file is 35MB, too big to upload here. If you like I send you a Google Drive link to it by e-mail...
Strange: if I play it in XnView MP, then color is OK. Also, all other video players show color. I included MediaInfo information about the MP4.