I've had similar problems in the past. This was the only guide that worked for me, after a week of relentless trying; see if it works for you. [GUIDE] How to hibernate to a swap file in Linux Mint 19.x - Linux Mint Forums 1
(I've posted about it here if you'd like to check it out as well: Attempting to hibernate results in screen going blank then back to normal, without powering off)