Howdy, one of my clients has been using the MarketPress pluign for years. We recently updated her site to 3.2.3 and now 3.2.4 and we've just noticed that people can no longer comment on any of her pages.
Here's a test URL:
WP - 4.7.5
PHP - 5.6.x or 7.0.x or 7.1.x
What's awesome is that the comment field is missing if all plugins are disabled save for MarketPress, and the theme is changed to TwentySeventeen, so it's definitely something in MarketPress.
Yes, I've made sure that comments are enabled for each page - even turning them off & saving, and then back on & saving.
If I turn MarketPress off, then the comment field appears on non MarketPress pages, if I turn it on, the comment field disappears.
(This is different than https://premium.wpmudev.org/forums/topic/how-do-i-turn-the-comments-fields-back-on in that the comments field is missing from ALL posts with comments enabled. That fix didn't work)