FYI, I sent an email to Roku tech support regarding the same issue (and more) with their own Roku Media Player version 5.0. Their response was to publish the 4.0 version as the upgrade to 5.0. IOW, they pulled it.
If RMP v5.0 reappears without the problem of the screensavers interrupting slideshows (they don't interrupt video streams), maybe you could check yours again without the workaround. FWIW.
https://community.roku.com/t5/Roku-Device-Features-Settings-Updates/Roku-Media-Player-5-0-broken/td-p/563345
