Wake-up problems

Hello!

I've been having problems for the last couple of days, my computer has problems waking up after not being used for a while.
For instance, if it's not used for more than 10 mins, the screen turns off, which is my energy setting, but I'm getting a black screen when I try to use it again, although sleep mode is disabled. CTRL+ALT+DEL wakes the computer, everything else seems to run normally, and there is no work lost.

It started happening for no apparent reason, the only change is the new monitor, but it was added about a month ago and I don't think that's the cause of the problem.

Any ideas about what might be the issue here? Please let me know what specs you might need to continue.

Thanks in advance!