Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
At first glance it seems bizarre that changing a theme or screensaver would impact apps loading, until you realize that themes/screensavers are (hidden) apps themselves, which take up both app installation space (when downloaded/installed) and operating space (when active/running), and have to contend with ever-larger OS updates in the same amount of device space (which is effectively the source of the issue).
You're welcome, and if anything similar happens again, try the same steps.
StreamerUser Roku Community Streaming Expert
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