ashdar_games_inc: The area you need to click in to select a ship should be the "tactical tile" that the ship inhabits. The tile is usually a square area that's strictly larger than the ship graphic (a few of the stations have rectangular tiles, but in all cases the 'tile' is a rectangle that's bigger than the artwork).
If a single left-click isn't toggling the selection state of a ship, then there's a UI issue that needs to be debugged here.
What's confusing is that it sounds like you have a very standard system, but, as you say, if this were a common issue, we would have heard more about it. I could imagine something connected to Windows UI scaling and/or very large monitors having the side effect of interfering with mouse clicks, but, I know we have other players using such settings/monitors who have been playing without encountering this issue.
The next logical thing to try is to switch to/from windowed mode during a tactical battle, and see if that changes the mouse click issues. If this is some sort of UI code glitch, there's a good chance that's it's specific to either windowed or fullscreen mode.
First: everything I described in this thread, prior to this, was done using full-screen mode. Everything in this post was seen while using windowed mode. I don't recall any differences in behavior by switching the modes. (Only difference is that in windowed mode there's a risk of me x-ing out of the application by mistake.)
Mouse/cursor behaviour on the 4X/map screen: cursor is a spacy looking triangle pointed to the upper left, no matter what you hover over. When you click and hold on the map, cursor remains the space triangle... until you move the mouse. When you move the mouse while holding, then the cursor changes into a Windowsy-looking white hand pointing up. Is this behavior as designed? The reason I ask is because click-and-hold operations typically change the cursor when you click-and-hold, not when you move the mouse. Also, click-and-hold operations usually display a grabby hand cursor rather than a pointiy one. Also, the pointy hand cursor does not look like it belongs in this space game.
Mouse/cursor behaviour on the battle screen: Note that I experienced the following both a) zoomed all the way out (preferred method of playing), and b) zoomed all the way in (thought there might be a zooming scaling issue; there was not). On empty field, behavior is similar to that described on map screen. When you hover over any unit (yours or enemy) then the cursor does not change from triangle, but a box is drawn around the unit. I had the same issues with selecting as I described in prior posts. I noticed that a single click, instead of selecting the unit, often changes the cursor to the pointy finger, which goes back to spacy triangle when the mouse moves. I wonder if click-and-grab mouse behavior is competing with selection? Maybe a micro-move of the mouse is causing the application to confuse my intent? If that was the case you would expect to see the map move a little - which I do not (unless it is too micro to be seen?).
That's all I can think of to try... Okay, I see you want me to try switching between full-screen and windowed actually during the battle. I did not do this. I only used the windowed option in your options screen. I think that the options screen is not available from battle (from memory, excuse me if I got that wrong). You want me to try switching using alt/enter then?
I will try this later tonight after football.