When I attempt to submit a review I’m running into a page that says “Provider information not found. Provider information is no longer available on TER. Is anyone else experiencing this?

If her profile is still up, then it's a programming bug.

Step 1. Are you starting at someone's Profile?  
Step 2. Are you then clicking the big blue "Review Provider" button on the upper right?
Step 3. Do you get partially filled in Review form or is that where you are getting the error?
or
Step 1. Are you starting by clicking the "Submit a Review" link to get a blank form?
Step 2. Are you getting a page that says:  
"Submit a Review
Is this an Existing Provider?
An Existing Provider has a Provider Profile/TER ID.
TER ID [                      ] Search
Step 3. Do you enter her Profile number and hit "Search"? Is that where you are getting the error?
.
Are you sure you are entering her correct Profile ID number? No typos? ID number and not some other number from her Profile page? Are you comfortable telling us who it is (Name or Profile ID)?  
.
Can you go back and try "Method One":  
Step 1. START on her working Profile Page.
Step 2. Click the "Review Provider" (as in "Review THIS Provider") button on the upper right and  
Step 3. Let us know if that works.

Impposter told you to do, which is  all correct, WHILE you are her profile page, copy the ad link.  Then when you click the Review Provider on the upper right, the next page that comes up will have a field to paste it there.  A review will not be accepted without a working ad link.  

...here with Sidney Fields who also played the landlord on the TV series.

I’ve had the same problem. No matter what provider I click on after it gives the terms for review it gives a message that the provider is not found. This is impossible. I have reported this to TER and they said they can’t replicate the problem. Obviously somebody else has replicated it. Maybe they can fix it now. I use iOS on my iPhone XR. It does the same thing whether it’s through Safari or another browser.

If so might try a non-phone submission to see if that works. I just submitted a review earlier today an no issues.

The only computer I have is from work and I am not using that one. I have a phone and an iPad. That’s all. If I can’t use those for TR I’m not gonna go buy a computer.

Have never used anything but an ai phone for reviews so that is not the issue.