Back "in the day" (5+ years ago) myBB was a valid solution... but like almost EVERY "free" script... the simple fact that they are dependent upon unpaid developers... their development process will ALWAYS lag paid scripts.
The bad thing is... if you really want somewhat "current" features.. you are probably going to be migrating to different "free" scripts regularly, or simply accepting the weaknesses in the "open source/free" platforms.
The other option is going to be breaking down and deciding to use a paid script which gets regularly updated (at least for bugs).
I realize that there are some here that are BIG "open source" fans (hi
@Arantor), but the simple fact remains... scripts that depend on license fees will be quickly fixed/updated... whereas those that are dependent upon those developers that offer their services for free will always lag behind.