Resume problem with NVidia card

I'm using Gnome 3 on FreeBSD 12.2 with a GTX 970 display adapter. The system suspends to RAM but does not resume, although it resumes with Windows and Linux on the same hardware.

A post in April recommended editing /usr/src/sys/dev/fb/vesa.c so that a line is commented out:
        bcopy(p, vesa_state_buf, vesa_state_buf_size);
        x86bios_intr(&regs, 0x10);
and then rebuilding the kernel. This appears not to work, although the new kernel works on my system as well as the old one. So I still can't use FreeBSD unless my situation allows me to touch a key or move the mouse at least once every 10 minutes or so. Otherwise a hard reset is required to get it started again.