ARGH! All connections lost!!!
Wow, that's a BIG bug! I managed to get Max5.1.0 into a state where no connections could be made anymore, and then, in any loaded patch, almost all connections were lost (except a few and signal)!
Hide/Show Connections was not part of it, of course. After throwing away the preferences folder, everything is fine again, but it is still freaky!
How I got there? I was undoing/redoing in a subpatcher a lot, then suddenly no connections could be made anymore, so I saved and quit.
Now I discovered that the above bug has a consequence in the patch saved when Max was in connection limbo (attached for testing): Trying to de-encapsulate [p add-std] within [p sequence-descriptors] crashes:
Thread 0 Crashed:
0 com.cycling74.MaxMSP 0x00122e8a jbox_getobject(_jbox*) + 6
1 com.cycling74.MaxMSP 0x001afe89 PatcherComponent::menu_dodeencapsulate(object*, object*) + 651
2 com.cycling74.MaxMSP 0x001b09a7 PatcherComponent::menu_deencapsulate() + 295
3 com.cycling74.MaxMSP 0x000deb87 object_handlecommand + 79
4 com.cycling74.MaxMSP 0x001ca7a4 patcherview_command(_patcherview*, symbol*, long, atom*, atom*) + 142
5 com.cycling74.MaxMSP 0x000b70d7 object_method_typed + 127
6 com.cycling74.MaxMSP 0x0015d206 jmenu_command_process(_jcommand*, unsigned long, object*) + 526
7 com.cycling74.MaxMSP 0x0015d24c jmenu_process + 46
8 com.cycling74.MaxMSP 0x000df422 interface_process + 24
9 com.cycling74.MaxMSP 0x00012aa5 app_eventhandler(OpaqueEventHandlerCallRef*, OpaqueEventRef*, void*) + 169
10 com.apple.HIToolbox 0x92adc13d DispatchEventToHandlers(EventTargetRec*, OpaqueEventRef*, HandlerCallRec*) + 1181