Notification Hub doesn't save installations nor registrations.

I am using the Azure Notification Hub REST API to work with notifications, but the /installation (for create and overwrite) endpoint doesn't seem to create the installations, while it returns a success response. I cannot read the installations after several minutes, nor send notifications.

I created a Notification Hub last week and it was working for a while (creating and reading installations, sending notifications successfully), but suddenly it stopped creating new installations and since I did delete the installations while testing the notifications stopped to work. Since then I was searching for a solution, and found out that others have had similar problems and one of their solution was to delete the non-working Hub and create a new one. Unfortunately the new one doesn't work either for me since its creation.

I'm was only trying to send notifications via FCMv1, and i could do that for a while, but suddenly the installations stopped working without any relevant changes from my side.

I also tried to work with the /registration endpoint, but the results are the same.