iMac mid-2010 11,2 Black screen after waking from suspend

I just installed Ubuntu 22.04.3 on my mid-2010 iMac a couple of weeks ago and I love it but suspend does not work. Everything else works except suspend. The system will suspend fine. It will shut off and everything but when I press the space bar to wake the computer up, the computer comes back up but the screen doesn't (it just stays black). I have to type in my password blind and then try to restart the computer by feeling my way around in the darkness. This is an old mac with an ATI Radeon HD video card and I've tried everything I could research online to no avail and putting all kinds of commands into my grub but nothing works. Any ideas?