Wmv files not playing

Just started with Shotcut (latest version). I can open wmv files and the audio will play but not the video. They’re originally VHS converted files. They’ll play on other platforms no problem (Windows 10 Film& TV, GOM, Windows Media Player etc)

Running Windows 10 Pro 64 bit, i7-7700HQ quad core, Geforce 1070GTX, 16Gb RAM so hardware should all be good.

Any ideas?