in the meantime (FYI):
i can reproduce this here with your cloned site. that’s a good thing.
and it transpires that this is a bug in the main wppizza plugin if only one gateway is enabled which is not a cash on delivery or similar pay in delivery gateway (i’ll spare you the minute details here). i’ll update the plugin accordingly and release an update tomorrow or latest the day after i would think.

will that update fix all issues ? hopefully one would think (certainly fixes things here and i cannot reproduce any errors with that fix applied), but i would suggest – when that update is available and you updated your version – you’ll keep debug enabled for a few days in case there are more as yet unknown issues . it will help track them down more easily if this should be the case

other than that, having looked at some of your settings, though not in minute detail , i would probably also suggest you

– a) set the timezone in WP->settings to an actual place (i.e London/Europe or whatever is appropriate) as opposed to UTC -1 as time offsets change for locations during the course of the year
– b) assuming you are not a charity, look at your tax settings. you are probably not tax exempt (i might be wrong of course) so entering your actual tax rates and then enabling “Prices include Tax” would presumably be a more accurate reflection of prices/tax (wont fix past orders, but going forward is likely to be a good thing to do, especially if using the reports->export ability for tax purposes – if you need to )

just suggestions/observations though. entirely up to you of course how you want to do things exactly