Gta 5 No New Mission Appearing

Rockstar support has a message on this topic:

Some players haven’t realized that certain missions are only available when playing as certain characters. This has most commonly been reported around Surveying the Score, Bury the Hatchet, and Deep Inside. It may happen elsewhere too. Try playing as all three characters for a while to see if the mission opens up. In some cases, missions will only appear after a certain amount of in-game time, so also try doing other activities for a while. Some missions are triggered by phone calls and those might not arrive when you are in certain locations, so be sure to not stay in the same spot if you are waiting for a call.

One possible work around, which has worked for some players, is to load the save file and use the “Quick Save” option to force a save to a new slot. After this is completed, load the new save and check to see if the issue is resolved.

Alternatively, in some cases, taking a cab ride, and then choosing the “skip” option, which forces a load screen has been known to resolve some progression blocks.

If you have tried all the suggestions above and cannot get more missions to appear, you may have a corrupt save file. This may happen for a number of reasons, including on rare occasions when applying a Title Update. If you think you may be affected by this issue, please reload a previous save file from before applying the TU. Unfortunately there is no way to fix save files once they are corrupted.

"Strangers and Freaks" is not one particular mission, but more akin to a "Side Quest" in other RPGs.

That is to say, it is not part of the main story path at all. So the first part of your question, "Why didn't it unlock a new mission?" is simply because there was nothing to unlock.

As to the question of what to do next, GTA V is unique in that you have multiple protagonists at once -- and certain missions are only available to start for certain characters. I would recommend switching to Michael and seeing what options he has available.