[Mailman-Users] No archive files but 2 lists taking up 50MB in cPanel?

I have 3 lists, going to mailing list administration and clicking on Go to list archives gives Private archive file not found for all.

But in cPanel mailing lists it says:

list 1 usage 14.98 MB list 2 usage: 37.72 MB

list 3 has usage in KB, which is what I expect. All are I believe setup identically

I don't have command line access to my cPanel - just FileManager.

How do I find out what these 50+MB are being used for and how do I recover the 50+MB?

Thanks!