I have been having this problem for a few days now. Haven't played it for a day or so to see if it would go away, it hasn't. I have a user on my playstation system that has playstation plus. All online multilayer benefits should be provided for me and they have been, until a few days ago. I am locked out from raids, strikes, nightfalls and all other multilayer content. Just a side note. My playstation plus ran out a month ago and have been using all the online features just fine until a few days ago.
Try reactivating the account that has Plus as Primary. Just deactivate and then activate again
I am having the same problem as you but on xbox one. I still have xbox gold though because everything else that requires it works fine. Just played VoG last night with no problems and this morning strikes, raids, and crucible won't let me in saying "get xbox live gold". Any ideas?
Well you really answered your own question. Congrats you got a free month.