Probably there is/are some syntax error/s on the page. Is this one of the demo projects? IF yes - have you changed anything on the page - i see, for example, the Bootstrap 4 framework is not included now.
I also tried copying code from test2.html page which does show the prop panel. But that doesnt seem to help either.
So can you tell the exact steps so we can try reproducing this? Did you just create a new project and selected the dynamic real estate demo project?
Then what did you, before you noticed the Properties Panel is gone?
I am not sure what I did yesterday to produce this. I think this demo project was already in the projects folder.
As a work around I can create a new page, and copy code from previous, since the panel seems to show on new pages.
That is weird.
I will try to recreate this locally.