Okay it happened again and this time I believe I know why.
When I activate it on a new site, it displays this message in the bottom-left corner of the theme modal windows:
“No Rollback Available: This is a non-www.remarpro.com theme”
If I run the “Force Plugin Updates Check” plugin to check for updates, the Rollback buttons then display in the bottom-right corner of the modals. If I deactivate and reactivate the plugin, the button continues to show properly.
It sounds like it waits until the first update check to figure out if the themes are from the repo or not. If someone is quickly installing this for a rollback, then that could be a problem. Maybe it could force a check on the activation hook like the Force Plugin Updates Check plugin?