Which table or table occurrence is the portal set up to show related records from? Does this relationship have 'Allow creation of records....." checked on the portal side?
Are there any scripts or script triggers firing during this process?
It appears maybe the foreign key in the relationship isn't being set, possibly creating orphan records.
When you create a record in the portal, commit, and it disappears, if you go to the layout based on the portals table occurrence, is the record there?
Or possibly you have defined a portal filter that is omitting the new record once it has been created.
Im an idiot. Started going through everything and looking at your recommendations and realized I had set the corresponding tables fk to a number instead of text to match the pk field.
Thanks for the help.