Thank you for letting us know Sarah :)

Now... @Gary

Have you seen this thread www.joomlaworks.net/forum/k2-en/45116-solved-image-upload-error-k2-7-and-j3-5?limitstart=0 ?

This is not a coding issue, as per PHP's manual the code is correct but in some versions the result is a string instead of an integer. The ;TLDR version is, we changed the code in the repo.

Yes this code fix works, but I would reiterate if I am changing code, then this is a code issue, or a PHP version issue, or a Joomla / k2 talking together issue. So code issue. I know Joomla changed a lot of code, have you guys asked them what they changed so that either they can fix this globally, or you can fix your code to make this work for everyone? I don't have access to PHP 7 or I would change it. I tried 5.6, 5.5, and a version of 5.4 and it didn't work without changing the code. Changing === to == does this affect other versions of Joomla, or higher version of PHP?

There is an explanation on that thread on how this as per PHP's documentation is correct and it only affects certain PHP versions.

This change is already included in our repo (DEV version) so the new version contains the == code.