The current online exercise system is still on Pega 7.1.6 and do support the Data Table Wizard. This feature is only removed in Pega 7.1.7. However, I do observe in my own experience that some tenant in the online exercise system do give some problem when using the Data Table wizard.
If you had to switch to PVS mid-course and require help to get you up to speed on your exercises, you can write to email@example.com to request for assistance.
Next issue is that the blue "Add a new Data Table" button does not open the Data Table form; although it tries to and quickly refreshes the workspace. Is this what you also encountered sometime previously?
You mention you've experienced a similar issue. What do you mean by tenant exactly? The server instance maybe? I'm on paex18-eu.pegacloud.com.