you can download the WicReset utility and use the Ink charge button , I have the impression that the ink was running low already before you refilled the ink. There are cartridges in the printhead carriage , they keep a small amount of ink which run low if the inks in the tanks get too low. This inhibits further ink flow even if you refill again. Do you have the valve switch at the ink reservoirs in the open position ?
Hate to say this but it looks like your L800 printhead may be failing between the Cyan and Magenta channels. Saw the same thing in the L800 we used for testing. I've not checked to see how the head is designed but my guess is that there's a grommet or gasket that's in there and that's not sealing properly, allowing a small amount of cross contamination.
Keep trying other options to see if the situation resolves itself but if not, it's worth looking for replacement printheads from aliexpress and doing a swap out with a new head.