AES and PHP 7.3.3

[GeeDeeJay]

I've been using AES on PHP 5.x for some time, but now my servers are being updated to PHP 7.3.3.
I tested my existing setup on 7.3.3, and using CBC mode (which is required) validation was failing.
No error messages are shown.
I set up a test on 7.3.3 which prints out the encrypted and decrypted outputs and the decrypted output still looks encrypted
The only clue I've found relates to changes in "__construct", but I don't know enough to decide if that may be the problem.
A demo is at:
http://fyefield.com/php_aes/aes_demo.php
GeeDeeJay