Bug in Split View for two Pages documents

After the recent High Sierra update (10.13.4) and Pages 7.0.1, Pages will still work in Split View with other programs like Safari, but stopped working with 2 Pages documents.

With a bit of a workaround, I am able to get Split View within Pages to work once—by clicking System Preferences > Mission Control > "Displays have Separate Spaces" (to unchecked), logging out, logging back in, and re-checking "Displays have Separate Spaces" logging out and logging back in again. Exhibit a:

However, once I move out of the Split View space, when I try to go back to it, each document will occupy its own space, and, once I get them out of full-screen mode, I am not able to get them back into Split View with the standard click-and-hold-the-green-circle.

Trying to get the two documents to share a Split View after the first success shows the error: "Not Available in this Split View".

Split View will continue not working (is that a thing?) unless I taking it through the logging-in-and-out workaround. I'm constantly jumping from Pages (and, as a result, ending Split View), so it's not a very useful way to work.

I'd love to know if anyone has found a workaround/solution to this issue.