I'd love to know more about this too (I'm the lead developer on Arq). Please email support@arqbackup.com with details if you don't want to post here.
Thank you!
I have already mailed you. There was no fix unfortunately.
OK. I found your email from Sep 2017, using Arq 4 and Amazon Cloud Drive. There was a problem with Arq deleting more old backup records than you expected, but without more information about what had happened in the previous year I couldn't figure out why it wasn't doing what you expected.
Can you provide more details? I'm also an Arq user and haven't noticed any problems.