Hi,
I am sorry for my slow response.
Do you have chr and SNP column separately or you only have SNPid column?
When there is no rsID column, FUMA tries to annotate rsID based on the reference panel using chromosome, position and alleles.
This error is saying that there were no SNPs that have matched chr and position with the reference panel.
If you can paste a couple of lines of your input file, I can see what is exactly the reason of this mismatch.
Best
Kyoko