Help – Mkv files playback looks scrambled and kaliedoscopic!

I just took a photo of how this mkv file is playing in Kodi (Krypton stable) on my Amazon Fire TV.

Why on earth is this happening and does anyone know how to fix it? The only similar issue I’ve found on these forums involved changing someone’s Nvidia settings on their computer, which doesn’t apply here as it’s on my Amazon Fire TV (Gen 2).

Here’s the backstory:

These are mkv files I have ripped from my own DVDs. I’m no video master, so perhaps I’ve done something wrong, but I just used the default settings in DVDFab to export it to mkv (H.264). The frame height is 720×552, Data rate 1020kbps and total bitrate 1212kbps. Frame rate is 25 frames per second.

As you can see subtitles are playing fine, and the audio is fine too.

The files play perfectly in VLC on my computer.

Can I (hopefully) fix this within Kodi, or will I have to rip all the files again?
Thank you for any advice!