Didn't find the feedback forum when I posted this, will take a screencap and post on support forum next time the issue occurs.
Anyway, I'm getting "Not a vaild feed" from time to time.
On the other site the feed hasn't been working for days, getting " wp_die 500" when opening feed in browser.
FYI
Windows defender trigged on this one.
https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?name=Trojan%3AScript%2FWacatac.B!ml&threatid=2147735503
file: C:\Eroge\Idol Hacked!\IdolHacked.rar
webfile: C:\Eroge\Idol Hacked!\IdolHacked.rar|https://dl-s14.downloadani.me/d/rx46xfe4aegsuwbyjdf5nsxhiyr33uccs7e3bi7zdhkf2xqiutjtd4rqejpkbi6z7p2afhny/IdolHacked.rar|pid:6260,ProcessStart:133761541241908727