I'm having problems with many of the exercises, but have found a work-around for all occurrences until now.
If I make a typo - say, miss a semi-colon - and then move the cursor off that line, your server doesn't recognize when I' put a correction in place. Sometimes, I check my corrected code with an online PHP parser, and it checks out ok.
Why won't your script engine / server recognize this?
Or if I want to write a loop, and don't put the end brace in until the loop is complete, this also seems to create the same problem.
Clicking on the Save & Submit Code button doesn't help. It just hangs up.
I've tried this in Firefox and Edge, on Windows 10.
My workaround has been to click on the PHP button at the top and then come back in to the exercise, but that's not working for me on the do while write-you-own exercise. My only option if to abandon this set of lessons and move on the next series on functions.
Even though it happens regularly and with many of the exercises, I've included my do-while loop code below. This code checks out ok on PHPTESTER.COM
//write your do-while loop below
$x = 0;
} while ($x<5);