Can't sign in using old [v5.5] editor

So have an old project I need to edit and republish.
Downloaded the 5.5 editor but when I launch the project, immediately after signing in with my login and pw I get a blank screen(attached)

Can anyone confirm whether this is a known issue with older projects (v5.6 or earlier)?

You recently install OS 10.15?

I’m on Mojave 10.14.5