No output after waking up

I have an LG display 34wk95u-W and a Mac Mini M1, the display is rated at 5120*2160 through USB-C only (not HDMI). when MAC wakes up from sleep the monitor detects that there is an input (so stays awake) and if i had a youtube video for example in the background pressing space plays the audio through the monitor but actually the desktop is not displayed (blank black screen shown) so video is not outputting via USB-C. connecting the HDMI port (lower resolution of 4k) i can get the desktop to display so video via HDMI works. restarting resolves this, until the mac sleeps again.

help?