Hre is what i'm seeing when switching workspaes :
Workspace 1:
Workspace 2:
Before the wide pill would indicate active workspace but now it's not and dot is only on first workspace. Note this is a fresh install of latest version zorin os pro 18
Hi, as a Pro user you are eligible for official support from Team Zorin. Have you filled out a support request form?
Do you have installed third-party gnome extensions? If yes, disable all user installed gnome-extensions for testing and check, if the activities button looks normal then. I read that various gnome-extensions or virtualbox can cause this.
You can also test if it helps to switch to Xorg or Wayland (depending on your used session). Logout and at login click on the cogwheel to switch between Xorg and Wayland.
https://www.reddit.com/r/gnome/comments/1fpygno/workspace_indicator_disappearing/
Do You have in the Settings set up dynamic Workspaces or a fix Numer of them?
Dynamic and I don't really have an extensions on tbh. Trying to stay very vanilla. They got better for a while but now back to doing it after most recent update:
So oddly i think it's isolated to the workspace 2 and dynamic workspaces don't seem to be working 
To get more than 2 workspaces i need to set static number of workspaces.
When dynamic workspaces are set, you only get three (or more) workspaces when you have apps on the other two ( three,...) workspaces.
Yeah i tested populating all workspaces with some app and now new ones are created 
If I may suggest an indicator that will allow you switch workspaces by clicking on it, you need the gnome shell extension "Workspace Indicator" by fmueliner. It also shows a indication of what's on each workspace.