First, to ensure that I interpret everything right: Which UUID is of the ssd-home you are currently using, and which UUID is of the timeout-affected hdd-home you want to use?
Second, we need to see the log files of the system because these contain the specific details of the error and its context.
If the error / timeout occurred on the current boot, provide the output of journalctl --boot=0
If the error / timeout occurred on the last boot, provide journalctl --boot=-1
For a full list of the logged boots see journalctl --list-boots which includes the start and end times of the logged boots. We need one that definitely contains the error/timeout.
I have seen before an error that had similarities, it was tackled in this thread:
https://discussion.fedoraproject.org/t/booting-up-reaching-emergency-mode-press-enter-1-sec-till-gdm-works-fine/69171
Depending on the configuration, it maybe needs to be considered that hdd’s have a much slower response time than ssd’s. I will review the disk configuration you provided when I saw the logs.