Editing

[AdelaideZumwalt1]

When I select on a feature and edit the related assembly attribute table using the attributes window I am able to tab and type, tab and type. There is one field that I actually have to click on to edit. Why is this? It is a string field, nothing seemingly unusual, but irritating. 

ArcMap 10.3.1

Table in a SDE Database (Not a feature class)

[DanPatterson_Retired]

arcmap version?

type of table?

source of table?

anything that may twig someone's memory