Better check the behavior settings for that field. If you've denied access to the field, that should not be possible.
And you haven't enabled "allow creation of records via this relationship" for the portal's table here have you?
I double checked the behavior setting and verified I have denied access. As for enabling "allow creation of records via this relationship" for the portal's table, where do I find/control that? I verified in my relationships table that record creation is not allowed in the relationship. TRhe relationship is TableName X TableName2 linking the TableNameID field.
If I delete the offending field in the portal (the one that allows an input when it should not), the next field in the portal then allows an input (but it doesn't when the first field is there). Any other ideas as to what's going on?
FYI I highlight the portal row so it goes to the related record in the TableName table.
What version of FileMaker and in what operating system are you using it?
I'd like to try and reproduce what you are experiencing.
Filemaker 13 Pro Advanced on a Mac OS X v10.7.5
I use windows 7, but the following file was created in FileMaker 13.0v1 advanced. The left hand portal allows browse mode access on each field. The right hand portal is a copy of the first, but each field was selected and the "browse" check box was cleared in the Inspector's behavior settings.
I then returned browse mode, saving the layout changes and tested. While I can enter data and create new related records in the left hand portal. I cannot reproduce what you report in the right hand portal. (I doubled clicked the relationship line between the two tables to select "allow creation..." for this relationship.)
Download the file and see if you get the same issue with it that you see in your file. IF so, then we have a bug to report over in Report an Issue.
PhilMod: Everything works fine in your test file on the Mac. As I was continuing to try to figure out the bug, I found it in a script that allows me end up on the correct portal row for a record when I next/previous in the TableName layout to highlight the same record in the TableName2 portal. Part of that code was to "goto Portal Row [Select; NoDialog; $goToPortalRow]. Previously, when "select entire contents" was left unchecked, it would allow the inputting into the first field on the portal row (which still seems as the wrong thing to do). Now that I have clicked the "Select entire contents" box, no input is allowed in any of the portal row fields.