HTML disappears when editing seeded resource alert template

Summary:

Hi,

As we are testing the seeded message template "Upcoming Birthdays" resource alert, we noticed that everytime we toggle between Rich Text editing mode and Source code editing mode, the original setup disappears.

Sample:

On source code editing mode:

On Rich text editing mode:

Selecting source code editing mode again:

As you can see, no changes have been made but the code disappeared. This makes it impossible to edit the template.

Is there a way to fix this?

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