Macbook pro M4 to two LG ultra wide monitors

recently purchased both of the above. when connected and switching on (startup) one of the monitors flashes on and off (unstable) the other black screened. The connections i'm using is usb-c from monitor to MacBook pro. After a number of minutes, in most cases, both monitors connect.........soooo frustrating!!! what the **** is going on??? spoke to both LG and Apple and neither had a clue!! Any help please?