iOS 12 and Instant Hotspot Not Working

I'm wondering if this is a problem for anyone else. and maybe offer a suggestion how to fix it.

Here's what I have:

iPhone 6s Plus - iOS 12

iPad Pro 9.5 - iOS 12

MacBook Pro - MacOS Mojave 10.14

All using the same iCloud account

When I try to use my iPhone hotspot, my iPad refuses to connect. I can see the iPhone available on iPad under Personal Hotspot, but when I try to connect to the hotspot it tries for a bit then returns an error "Unable to start personal hotspot "Brian's iPhone". I have tried starting with spot off and on.

Note: before the iOS 12 upgrade, I was able to connect, but it usually took more than one attempt.

Also note: earlier today when I tried connecting to the iPhone with my MacBook I successful.

My research has lead me to try the following multiple times (with no success):

Log out/in of iCloud on iPhone and iPad

Reset network settings on both iPhone and iPad

Reset all settings (factory reset) on iPhone and iPad

Is there some trick to get this to work?

Is there something anyone can suggest I may have not tried?

Any advice and suggestions are welcome and appreciated.

Thanks in advanced.

Brian