What I did:
Entered preformatted text enclosed in backticks and then tried to change the format of text on subsequent lines to not be preformatted.
What happened:
All text on subsequent lines were preformatted and would not change to other styles even when selected from the style menu.
What I expected:
I expected the style to change to that which was selected.
When I type text without the backticks and change the style using the style menu I do not encounter this problem.
Things that might be helpful to know (Agenda version, OS and model, etc):
Version 9.1, Mac OS 10.15.1, MacBook Pro (15-inch, 2019)
I experienced this problem prior to upgrading to Mac OS Catalina