Hello,

I have been experiencing issues with preview, together with caption.sty and float.sty.

You will find a minimal example that triggers the errors documented below, while 
compiling without errors outside of preview. If you
remove the package caption.sty, or the package float.sty, preview
works.

If you change the H option on figures to !h, preview works again ; however, in my actual
work, where I discovered these errors, even after swapping all [H] to [!h], I still get the
"Extra }, or forgotten \endgroup." error. I don’t know if this is a usual behaviour of preview
(as I guess cutting a tex doc in chunks can be tricky)
if not, please let me know and I will try to build a minimal example.


Best,
-Anatole