Strange Issue with Ann Text

I have an XREF (units m) containing Annotative text & leaders. When editing this XREF in place on another drawing (mm) then ann text goes haywire. I've tried adding ann scales to text in m & mm but it just goes tits up.

The text is easy enough to scale correctly - however the leader attached to the text goes rediculously large, almost like the landing gap is huge, and nowhere near the text.

Any ideas?

After further investigation it appears to be an issue with one of the scales. Even in the XREF, one of the scales has made the leaders position scale to a rediculous size. I have no idea why it does this. So still looking at solving this hopefully.