Custom fields don’t filter correctly

I’ve just started playing with Events Made Easy and found the filterform isn’t working correctly with multi-value custom fields.

Steps to re-produce:
1. Create a custom field, field type = Checkbox
2. Add #_FIELD{1} to “Event list filtering format” in Settings.
3. Create some events
4. Create a page with just 2 shortcodes: [eme_filterform][eme_events]
5. View the new page and filter by the custom field (say option 1).

What I expect to see:
Only events with option 1 selected should appear.

What I see instead:
Events with any options selected are showing. Only events where the custom field is empty are hidden. This is true no matter which combination of options I pick in the filter.

Thanks for making this awesome plugin. I’ve tried many plugins but this is the most customizable one I have come across.