Glitch Editing Immigration Event?

GFre

I wanted to edit an immigration event to add a date range (since there were two years on the census records), and then include some information from the obituary in the reason; however, the save button won't light up unless I edit the 'description' or 'place of immigration' first.

Is this is a glitch, or does it happen because the entry isn't considered complete without one of those? I assume it wasn't what was intended.

Here's the example: https://www.familysearch.org/en/tree/person/details/LWK9-NJG

Thanks.