HI Bruno,
I’ve had a look. Took it to the ‘Place Order’ stage and yes the place order is greyed out.
I’m wondering if this is maybe a combination of memory and javascript error?
Reasons for thinking this:
1) the only thing related to amr-users plugin is the front end css, (you can stop this stylesheet loading in the settings – tick “use my own theme css only”). That css doesn’t do any greying out and using ‘Inspect element’ I cannot see any of it applying to that div or anything in that div.
There appears to be some ‘BlockOverlay’ stuff that is causing the greying out – (not generated by my plugin)
https://i.imgur.com/PyqtaYF.jpg
2) if I refresh the page it is initially NOT greyed out. This says to me that some javascript is greying it out after everything has loaded (and possibly is supposed to later undo that?)
I’m by no means a JS or Jquery expert, but Using Firefox Inpspector on a refresh I did see an admni-ajax internal server error? see https://i.imgur.com/tDHQMWw.jpg and google indicates that may be related to checkpout problems.
https://www.google.com.au/search?q=woocommerce+admin+ajax+internal+server+erro
googling things like:
https://www.google.com.au/search?q=woocommerce+place+order+not+working and
https://www.google.com.au/search?q=woocommerce+place+order+greyed+out,
it seems that there are a number of varying causes for a woocommerce checkout grey out and they seem to be Javascript related. My plugin does not loading any js on the front end (I prefer things to work without js).
Some of the links also mentioned memory issues. If amr-users was one of the last plugins you activated then it may be simply be that it took your site over the memory limit. You could test that by maybe deactivating other plugins and then reactivating them – if it’s the most recent one that always causes the problem, then it’s definitly memory And of course you can checking/testing your memory.
If it is memory related it would definitely be worth knowing and understanding how close to the wp/php limt it is running that as you may find that the problem is intermittent and/or comes back when you make a change to the site or a theme or plugin updates.
Aside:
I ran Yslow on it as it nicely lists the stylesheets and scripts, just to try get an idea of whats going on in that page. That page has 47 (!) external scripts loading.
Do post back any updates for benefit of any others. Good Luck.