Hi X,
I came across this problem:
When I tried to import a .json file from integrity 01 (X CUSTOMIZER SETTINGS) i got this error:
This does not appear to be a WXR file, missing/invalid WXR version number.
I solved it by adding this at the beginning of the .json file:
<wp:wxr_version>1.1</wp:wxr_version>
So for me it’s not an issue. But I thought i just shared it with you incase some other members face the same problem!
Cheers