Edit:
If it says that no ground services are available when you request it through the Ctrl+F12 menu, try moving to another stand (ex: if you are parked at a "Small" stand, try to park at a "Medium" stand, and if that doesn't work, try one of the "Heavy" stands.
From experience, anything the size of a Boeing 737 or an Airbus A320 should be able to use all stands depicted on
this chart, apart from stands 2, 3, and maybe nr 7. If you are flying something bigger, say like a 757 or 767, try using stands 46, 48, 49, 50, 51, 53, 186 or 187. The largest aircraft, like the 777, 787 and 747s use 49, 50, 51 and 53 only if I remember correctly. As for Pier North, I haven't tried using any of those gates while flying anything bigger than a 737.
Cannot speak for the other scenery that you mentioned, as I haven't tried it.
If it says that there are no gates are available when you access the scenery editor, then unfortunately there is nothing else I can think of, but reinstalling the scenery with a freshly downloaded installer.
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