I have downloaded “Latest-Ardusub Raspbian Image” from Downloads section. Could you please check if the link provides v.0.0.21. Because I have checked that the size is exactly as in v.0.0.20 and Etcher says it is v.0.0.20.
I have RasPi connected to internet, with Companion Computer v0.0.20. I cannot see “Update Companion” button, but “Download Update: No Updates Available”.
That’s so annoying! I must have tried a dozen times this afternoon. I tried again for a screenshot and it worked! Slowly downloading now - I live in the U.K. nothing happens quickly!