So, I removed tyre to replace a damaged valve, all went easy enough but I just can get the bead seated

I've changed dozen of tyres and never had a problem like this

It like the tyre is not wide enough for the bead to be seated on the rim, but obviously it if because its the 1 that come off

I've tried putting a strap around the tyre to try and close the gap but I just can't get it done

​​​​​​My compressor is working fine it's just the gap is too big no matter how I position the tyre

Any ideas?