auto-youtube-subscription-playlist-2: Cannot query for user RedstoneQuarry

I recently added “RedstoneQuarry” to the sheet for this channel: https://www.youtube.com/c/RedstoneQuarry/videos Since then, it got stuck on that entry with the debug sheet message “Cannot query for user RedstoneQuarry”. When I use “UUW_OAaMdUH3fF00fh8_Koeg” instead, which is the playlist ID of their automatic “all uploads” playlist, that fails with “Cannot query for user UUW_OAaMdUH3fF00fh8_Koeg”. Only the channel ID, which is “UCW_OAaMdUH3fF00fh8_Koeg” (C as second character) works, which can apparently only be obtained by saving the HTML source of the channel page and finding the »"externalId":"UCW_OAaMdUH3fF00fh8_Koeg"« element in some long JSON object (or maybe it’s always the playlist ID, but with a C?). Other short channel URLs, like “slicedlime”, “TheHappieCat” or “SiberianHat” work fine.