Marketpress number_format()

I into the main sites admin and notice some sitting orders there with a php error, these are orders made in client sites:

Warning: number_format() expects parameter 1 to be double, string given in /public_html/wp-includes/functions.php on line 155

See screen for example.

The orders in this screenshot were all made at client websites, They all had values of between £25 and £35. All use Paypal Express.

- Why do they show in the main sites "manage orders" area? (main site = master site in a multisite install)
- Why do they all show the wrong value, ie £0?
- None show the actual shop the purchases were made in.

Orders have been made at other client websites with success that don't show in the main sites "manage orders" area.

The ones producing this error all have one common denominator, I created their sites first with my e-mail address. Addresses have obviously been changed since the client took over management.