If the forms are bound, you've put the record in edit mode and the result needs to be committed. I can't imagine the purpose of your button "enter" event so you might have to explain why you think it's necessary since it might be playing a part in the problem. You could try adding
If Me.Dirty Then Me.Dirty = False
What seems more of an impending future issue is to save multiple fields in one. You can't do much with it if you intend to query on the field (as an example), it's no good as an index and it constitutes a calculated field, which you should not do in most situations. This has to be one of those situations.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.