Research Question - An Adagio for String Quartet attributed to Beethoven

[Graham1973]

I was looking through a second hand copy of the 1934 (Reprinted 1968) book "The Master Musicians: Beethoven" (Author, Marion M. Scott) and spotted a reference to an Adagio for string quartet attributed to Beethoven that (Presumably in 1934) was held by the Prussian State Library.

I would be very interested to know if it:

a). Survived the war.
b). Had the composers identity confirmed.
c). Had been published.

Any help would be gratefully appreciated. To give context the same paragraph discusses the Duet WoO. 32 as being a work worthy of being mentioned as an 'extra' to the list of Beethoven's chamber works.

[Graham1973]

I'm bumping this 'Research Question' because I've had little success trying to pin down what the piece described in the OP is. I've tried contacting 'The Unheard Beethoven' with no luck (or response.), to the queries I posted in the OP, I would like to add the following:

d). How complete is the movement (eg. Is it a complete composition, or just sketches.)
e). It is a transcription of another piece by Beethoven (I am aware of the Adagio in F major, WoO.33 No. 1 for Mechanical Clock being compared to the equivalent slow movements in the Op. 18 quartets and existing in a transcription for Organ (Played on Hyperion album CDA67060).)

Any help would be very gratefully appreciated.

[Notenschreiber]

A very vague hint: There is an Adagio in the Staatsbibliothek Berlin (compare https://opac.rism.info/search?id=1001022888) from Beethovens friend
Nikolaus Zmeskall. Maybe the authorship of this music was not clear in 1934.