We are experiencing an issue where after updating the WP core to 5.4rc the templates of a page are no longer recognized, like so:

Reverting WP core back to 5.3 seems to solve the problem and the template along with the "Edit with Elementor" button re-appear.

This test was run on a clean db with only Elementor & Elementor Pro (latest) plugins activated and Hello Elementor theme.