Yes, I also have this problem. The "solution" was to rollback to template 7.0.2, as this weird blank screen behavior was introduced in 7.0.3 to correct a bug related to a distortion in the splash screen when in landscape.
Or you can continue using 7.0.9 and revert only the commit related with this issue:
(just remove the lines in green, and add the lines in red)
PS1: To do this, you have to clone the React Native Template from Github and edit the changes prior to generate a new APK.
PS2: Or you can edit online by typing . (dot) on the page to call the online VSCode editor (a very nice feature of Github).