I am unable to recreate this problem on my test system. I tried to reconfigure your Groups/Access levels so they match my system but it made no difference. I think the only way to resolve this would be to insert debug code into your system or to get an Akeeba Backup of it for testing offline. Both of these are outside of the scope of what I am willing to do as just another user.

tonyp will have to assist. Please post the access instructions in the Site Details section so he can take a look as soon as he reads this posting and so that he doesn't need to ask for them delaying the resolution.

Sorry I couldn't be of more help.

tonyp please help us on this issue asap. Kindly find the site details.

Please check 'Testing RSVP Pro' template. The fields 'Attention To' & ' Invoice No' are restricted to superusers.
Those fields are not appearing in front end (http://events.ewi.org.sg/index.php/component/jevents/eventdetail/10/-/test-rsvp-pro?Itemid=101), but under RSVP Pro -> Sessions, we are not able to edit/add our(superuser) input to those two fields. Please see attached screenshot for your reference & help to find a way to edit those superuser accessed fields.

Note: we have also set the field access level to 'SuperUsers'