Unable to remove a string in the Unsynced lyrics field

All of my lyrics have the phrase " eng|| " before the lyrics(eg: eng||There is a place). I want to remove them as they cause problems when viewing lyrics.
I have created a replace action:
Field : UNSYNCEDLYRICS
Original : eng||
Replace with : (I didn't put anything in that field)

I get the message " formatted tags in xx/xx files. 0/xx replaced. " after running the action. However, nothing happens. Since these are also the first 5 characters, I've also kept the original field as " ^.{5} ". That doesn't work either. Whole expressions and case sensitive fields are unchecked. I've also tried replace with regular expression which doesn't work.
Can anyone help me out?
EDIT:I can replace it with another string, but removing it does not work

Actually, you have to have some kind of language token as prefix in the field.
The default is "eng||". So if you remove it and MP3tag finds that there are no 3 letters followed by 2 bars, it adds them.
If you replace the eng|| with e.g. xxx|| it would mean that there is no specific language. But as I said: you have to have some token.

What kind of trouble do you have with the lyrics?

The lyrics display without line breaks. If I remove eng|| they display fine.

Where do you check the display of the lyrics?
Just a note: without the language token, the field has a non-standard format.

On my android phone. I've tried many lyric viewers and they all show the same behavior. I even contacted the devs, but they said that they only used a library to read the tags. Could that library be the problem?

Well, who knows?

The line breaks do show if you remove the eng|| part? Then it is definitely the library.

You could try to replace a single line break with a double one:

Action of the type Format value for UNSYNCEDLYRICS
Format string: $replace(%unsyncedlyrics%,$char(13)$char(10),$char(13)$char(10)$char(13)$char(10))

Experiment a little to see if you need only the $char(10) or only $char(13) and if it makes any difference at all.