No stem on chord-tremolo

[Colin Hunt]

Hello community,

I've begun my first piano score in Lilypond after studying soundsfromsound's great introduction series. This code shows my problem:

\version "2.22.0"

\language "english"
\relative
{\time 3/4\clef bass
 \repeat tremolo 12 {b,32 ds} |
 \repeat tremolo 12 { <<b32 fs'>> <<b ds>> } |
}

The first measure is just as I'd expect, with two beamed dotted notes. The second measure is messier. There is no beam, and the tremolo covers other elements like the dot on the low B. The lilypond log says:

Starting lilypond-windows.exe 2.22.0 [Untitled]...
Processing `C:/Users/colin/AppData/Local/Temp/frescobaldi-wy5qr1tu/tmp1d_yxtvp/document.ly'
Parsing...
Interpreting music...
Preprocessing graphical objects...
programming error: Grob direction requested while calculation in progress.
continuing, cross fingers
programming error: Grob direction requested while calculation in progress.
continuing, cross fingers
Finding the ideal number of pages...
Fitting music on 1 page...
Drawing systems...
programming error: The beam should have a direction by now.
continuing, cross fingers
C:/Users/colin/AppData/Local/Temp/frescobaldi-wy5qr1tu/tmp1d_yxtvp/document.ly:7:25: warning: weird stem size, check for narrow beams
 \repeat tremolo 12 { <<
                        b32 fs'>> <<b ds>> } |

C:/Users/colin/AppData/Local/Temp/frescobaldi-wy5qr1tu/tmp1d_yxtvp/document.ly:7:37: warning: weird stem size, check for narrow beams
 \repeat tremolo 12 { <<b32 fs'>> <<
                                    b ds>> } |

Converting to `document.pdf'...
Success: compilation successfully completed
Completed successfully in 1.0".

I would like to make this measure look like the first, with two chords beamed together. I also have use for this version without the beam, if I could figure out how to get the tremolo out of the way of the dots. Any help is much appreciated on either of these fronts. Thank you all for your time,

Colin