Ok.
With 7z File Manager, looking the 7z files with the 'bold problem', i see where is the bug/problem.
All 7z files with BOLD font are with "Extended Attributes" like D_ or A_ in 7z File Manager (9.20 version)
And MultiCommander can´t manage this type of 7z (No size, date, info etc.) and is impossible to view
files under folders. Internet not show info about 7z with Attributes D_ A_.
Look this pic capture from 7z File Manager.
May be i´m completely wrong with my view of the problem, but i´m try to help you.
Thanks.