I had the same issue, i changed the color mode from the File> Document color mode, this worked once for some files but for some other files it didn’t, so i think i discoverer the problem which was in the swatches, when i double clicked on one of the colors this brought the swatch options i found out the the color mode for this color was set to CMYK although the AI file is set to RGB so going through each color swatch and setting it to RGB solved the problem for me hope someone might find this useful