Something similar happened to me.
single case, eu19xxx
I haven't been requested to send docs so far, even though I submitted ds260 on
May 8th and resubmitted end of July after unnecessary unlock.
However I sent them docs proactively on June 16th.
End of October KCC, responding to my general inquiry, confirmed
having received my documents and currently processing them.
20 days later, responding to another inquiry, KCC says they have
not received my documents (the same-named KCC contractor signed both emails) !?
I resent my docs right away and sent yet another email asking them what's going on and which of those 2 information is now relevant to my case and how they confirmed the reception of my docs 20 days ago, while now saying they dont have them.
Next day (after resending docs) responding to this inquiry above they (again) said my DS is processing blah blah, but AGAIN "Kcc has not received your documents"
At this point I realized I'm just going to patiently trust the process and not bother them anymore. Throwing inquiries at KCC is only good for wasting their time and your hope. Cases move whenever KCC decides to make them move, as simple as that