You probably bought it on Alliexp. Provide a link to this monitor - I will look
And try:
type in userconfig.txt
hdmi_group=2
hdmi_mode=87
hdmi_cvt=1480 320 60 6 0 0 0
But first, replace the image files (2) and try
custom_7 (1480x320).zip (235.2 KB)