Loading a session that had startify help page open causes the page to not be rendered correctly #521

To reproduce

1. Open Neovim (v0.6.1)
2. Run :h startify to open startify's help page
   
3. Run SSave to save current session
4. Exit Neovim (I used :qa)
5. Open Neovim
6. Open saved session
7. Startify's help page isn't displayed correctly
   

Note: this occurs regardless of what other buffers are open.

Expected behavior

This only seems to happen with startify's help page specifcally.
Doing so with other help pages works fine, and startify's shouldn't be any different.
Ex:
Opening help page and then saving session:

Reopening session: