Decimal separator: period
The dates in multiple places include a day of week, making them too long to display in the available space. The format appears to match my selected Windows 10 Regional formatting option. If I change that option "English (United Kingdom)" instead of "English (United States)" and restart the application, then the problem goes away.
Note that the Completion date for creating a Shipyard Task (near the bottom of the Shipyards screen, rendered in green) does show up correctly without the day of week, so whatever you are doing there might work in other places. Using an explicit format rather than the system format may be useful given the fixed amount of space available for rendering dates in most places.
* Economics window > Industry tab > Completion Date
* Economics window > Shipyards > Completion Date (for Shipyard activity in the list of shipyards)
* Economics window > Shipyard Tasks > Completion Date
* Economics window > Research tab > Completion Date
* Economics window > GU Training > Completion Date (haven't tested yet, seems likely given the trend)
* Commanders window > Date of Commission
* Commanders window > list of events in the top right
* Events window > the date in the Race column
Example from Research tab: Sunday, June 11, 20. . .
The inability to view the year makes this a bit painful.
