To the original poster: redownload YellowBarDynamic and the progressbar will have been fixed for you. YellowBarDynamic and its Unicode variant were both updated on the Theme site.
The progress bar tag apparently needs its own line just like the picture tag.
And it must come before any other "text" tags or else those won't show up. I never saw this peculiarity documented.
Originally this syntax worked fine, but now it doesn't show the progressbar:
%V(0,0,-,8,2)
%al%pc%pb(32,0,66,6,pb.bmp)%ar%pr
%x(a,pbbackground.bmp,32,0)
Now this works on build r27759:
%V(0,0,-,8,2)
%al%pc%ar%pr
%x(a,pbbackground.bmp,32,0)
%pb(32,0,66,6,pb.bmp)
This fails to show %pc and %pr on build r27759:
%V(0,0,-,8,2)
%x(a,pbbackground.bmp,32,0)
%pb(32,0,66,6,pb.bmp)
%al%pc%ar%pr