On Xbox rewards I had enough points to be able to purchase just over £40 for an item (they were all out of stock of anything decent so with being told these points would transfer to Microsoft rewards I left them on there.)
Unless the conversion rate is so terrible that it amounted to only 80 Microsoft rewards points or £8 on my Microsoft account I have still not received either a conversion of points from Xbox rewards to Microsoft rewards or a credit on my account anywhere near equal to what would have been on my Xbox rewards account.
Emailed Microsoft and got a generic answer which didn't explain anything correctly then referred here.