metronome mark not shown without other markup in same place

[Paul Scott]

I can't seem to get a metronome mark without putting a markup in the 
same area.  The \tempo 8=120 in the example doesn't appear and either of 
the other two in the example will disappear if the nearby markup is removed.

Also as someone else pointed out metronome marks are substantially 
larger than what I have seen in other engraved music and I didn't find 
any property to reduce it's font size.

\version "2.3.23"
#(set-default-paper-size "letter")
#(set-global-staff-size 20)

\header {
    subtitle   = "No metronome mark without markup"
}

globalc = {
    \override Voice.TextScript #'padding = #4.5
    \override Score.MetronomeMark #'padding = #2.5
    \time 4/4 \tempo 4=60 s1*5 ^\markup\bold{ Allegro }
    \time 3/4 \tempo 8=120 s4*3*3
    \override Score.MetronomeMark #'padding = #3
    \time 6/8 \tempo 4.=116
    s8*6*4 ^\markup\bold{ Allegro }
    s8*6\ff s8*6*3 s8*6
    \bar "|."
}
clic= \relative c''' {
    R1*5 R4*3*3 R8*6*4 c8-> r4 r4 r8 R8*6 a8-> r4 r4 r8 R8*6
    d,8-> r4 r4 r8
}

\score{
    <<
        \set Score.skipBars = ##t
        \new Staff << \globalc \clic >>
    >>
}


Paul Scott