The new message tab does not preserve line breaks in sent messages. They do send with the line breaks, but the message window does not show them. This can make sent messages very hard to read/understand. Especially when you are sending a list of openings to someone wanting to book. The list on our end ends up looking like this:

Hi Name, We have the following openings: Tuesday at 2:00 with Kate Wednesday at 4:00 with Steve Thursday at 12:00 with Jane Friday at 1:00 with Marcy Please let us know if you would like any of those appointments

When the guest says they want the Friday opening, it can be hard to tell what the opening is, and who it is with since everything is mushed together instead of on the separate lines as it was intended.

After further testing, line breaks in received messages are not shown either.

When viewing messages in the client profile the line breaks are all present. So, it appears to just be something with the new message window.