This seems to be an endemic problem in using Macbook Pro as a hotspot to support wifi connection to other devices. In any case, if nothing works then I try the below, which I have confirmed few times that it does work.
1. Turn off all devices that you wish to connect to Macbook pro hotspot. These will be Iphone, Ipad, and all other computers sharing the hotsopt.
2. Turn off Macbook pro.
3. Re-start the Macbook pro and confirm by using the browser that Internet connection is alive on Macbook.
4. Go to System Preferences, then click on network sharing and uncheck the Internet sharing checkbox and then Internet sharing from Ethernet to WIFI will show an off status.
5. Recheck Internet sharing checkbox. It will ask your permission to start Internet sharing. Click ok (or any affirmative button).
6. [I have not seen much advantage of doing this: you can click on the lock on the bottom ostensibly preventing further changes. I have found that in spite of locking changes they do happen anyways. However, if locking worked for you in past then go ahead and lock the changes].
7. After few minutes, start your first hot spot sharing device. If that successfully connects to hot spot then turn on and add all additional devices one by one.
Hope that works for you. Good luck and best wishes. 🙂