Hi @Herbert_Kaindl,
Here’s what we’ve concluded with QA.
There are real issues affecting special characters in Filter, particularly on iOS Remotes. See here, for instance: iOS Smart Punctuation Breaks Filter Input with Certain Special Characters [Ticket In]
We can confirm @Simon_Arnold3 and @Dirk_De_Taey’s conjectures that 1) non-library items are excluded from this view and 2) matches in other metadata fields - like performer or songwriting credits - are prioritized over matches in the Track Title or Album Title in filter results. This is a feature, not a bug, of this cross-indexed list of Recordings, and this is functioning as designed. If you have objections to the current sort functionality while sorting Recordings by Popularity, I recommend raising this same issue in Feature Suggestions.
There’s an additional UI bug that the team has documented while filtering results when sorting Recordings By Popularity. The filter will sometimes initially display non-library and library results before further filtering, and occasionally, this can even cause grey placeholders to flash in place of artwork. We’ve ticketed this item for review, but since it’s not the issue reported here, we’ll allow this thread to close.
Thank you again for the report.