Sorry, I didn't finish that comment. I don't, know what is going on but yes, try a different card. Also, always format the card in the camera. I expect you did, but I thought I would mention. There is no point in not using lossless compression by the way.
Something does not seem right.
Uncompressed raw files for the X-T5 are supposed to be around 80MB, call it 85MB just to be safe in that assumption. 183 x 85MB = 15555MB, which is about 15.6GB. Even if you are using full sized, fine jpg along with the uncompressed raw files, you would not come close to filling a newly formatted 64GB card with 183 shots.
Maybe try a new card?
If your image frame numbers with the X-T5 are "99xx", my first thought is that your X-T5 is set for "Continuous" frame numbers and your card has run out of available numbers up to 9999. But, that your X-T20 is set to "Renew"
Go to Settings > Save Data Setting > Frame No. and choose "Renew". Reformat the card.
Hope that helps.