Hi,
I am sorry for the slow response.
It could be filtered by MAF but SNPs that are not present in the selected reference panel also get filtered out, so it's most likely either of that.
In addition to that, FUMA also checked alleles and if the input alleles don't match with the reference panel, they are filtered out from the clumping.
Please let me know your job ID as well as your input for SNPs you are expecting in the results (so that I can check if the allele mismatch is the case here).
Best,
Kyoko