We've upgraded our EPiServer installation from 7.5 to 10 (10.4.1) and after working through all the breaking changes, everything works except some issues with the on page editing view.

• When first navigating to a page the on page editing view loads as it should. But if we change view to the property view and then back to on page edit the view is never loaded. The toggle button just spins and nothing happens. Refreshing the page will load the on page editing view.
• When on the property view of a page and navigating to a new page the on page edit view isn't loaded. However, the top bar with page breadcrumbs and the toggle view button is updated. Pressing the toggle view button in this state will load the property view for the correct page.
• When publishing changes, the on page edit view isn't loaded. But as above, the top bar is updated.
• When selecting a block to edit from a page property view the on page edit view loads, but if we view the property view for the block and then try to go back to the page with the back-button, the on page edit view gets stuck the same way as the other issues.

All of this seems to happen for all pages regardless of type, no errors are thrown and no requests seem to get stuck. 

Appreciate all the tips in any direction, our troubleshooting have been fruitless so far.