After updating Date, missing repeat UI

I have the repeat UI in new date fields, but not in fields from existing content types. We are updating form a MUCH older version of Date.

When looking at content_node_field, I noticed the older fields are missing s:6:"repeat"; and s:16:"repeat_collapsed"; that get added to new repeats. I've tried modifying the content type so the date is not repeating and then adding the repeat back, but this doesn't not add the repeat option to the field. Turning off repeat on a new field doesn't remove the s:6:"repeat"; from the global_settings column. Likewise, adding a new field with no repeat has those settings.

What is the logic here? I'm reluctant to add that to my old field until I understand why it's there.

No repeat UI...

a:5:{s:11:"granularity";a:6:{i:0;s:4:"year";i:1;s:5:"month";i:2;s:3:"day";i:3;s:4:"hour";i:4;s:6:"minute";i:5;s:6:"second";}s:11:"timezone_db";s:0:"";s:11:"tz_handling";s:4:"none";s:6:"todate";s:8:"required";s:14:"default_format";s:5:"short";}
a:2:{s:5:"value";a:4:{s:4:"type";s:8:"datetime";s:8:"not null";b:0;s:8:"sortable";b:1;s:5:"views";b:1;}s:6:"value2";a:4:{s:4:"type";s:8:"datetime";s:8:"not null";b:0;s:8:"sortable";b:1;s:5:"views";b:0;}}

Has repeat UI...

a:7:{s:11:"granularity";a:5:{i:0;s:4:"year";i:1;s:5:"month";i:2;s:3:"day";i:3;s:4:"hour";i:4;s:6:"minute";}s:11:"timezone_db";s:3:"UTC";s:11:"tz_handling";s:4:"site";s:6:"todate";s:8:"required";s:6:"repeat";s:0:"";s:16:"repeat_collapsed";s:0:"";s:14:"default_format";s:5:"short";}
a:2:{s:5:"value";a:4:{s:4:"type";s:8:"datetime";s:8:"not null";b:0;s:8:"sortable";b:1;s:5:"views";b:1;}s:6:"value2";a:4:{s:4:"type";s:8:"datetime";s:8:"not null";b:0;s:8:"sortable";b:1;s:5:"views";b:0;}}