Joshua David Nelson on "[Plugin: Simple Page Ordering] SyntaxError: JSON Parse error: Unrecognized token '"

I’m getting the following error on custom post types and yes they are hierarchical...

SyntaxError: JSON Parse error: Unrecognized token '<'
http://website.co.uk/new/wp-admin/load-scripts.php?c=1&load%5B%5D=jquery-core,jquery-migrate,utils&ver=4.3.1 line 5

Console...

SyntaxError: JSON Parse error: Unrecognized token '<'
parseload-scripts.php:1656:266
parseJSONload-scripts.php:1656:266
parseJSONload-scripts.php:3235:450
update_simple_ordering_callbacksimple-page-ordering.js:1:118
jload-scripts.php:1005
fireWithload-scripts.php:1050
xload-scripts.php:1829
bload-scripts.php:1918:265

Any ideas, it does re-order but just hands with the spinny icon.

https://wordpress.org/plugins/simple-page-ordering/

I'm getting this error as well. It just spins, I have to reload the page after each drag-and-drop. Mine are not hierarchical (using 'page-attributes' instead).