Transpose of Bb with clef declaration fails

[seisiuneer]

Interestingly

K:BbMaj clef=treble

is OK

X: 1
T: Transpose Bug Demo
R: Jig
M: 6/8
L: 1/8
Q: 3/8=120
K: Bb clef=treble
GAG GAB|ABA ABd|edd gdd|edB dBA|

X: 1
T: This one is OK
R: Jig
M: 6/8
L: 1/8
Q: 3/8=120
K: BbMaj clef=treble
GAG GAB|ABA ABd|edd gdd|edB dBA|