I wish I could remember the particulars with something that happened to me similar to you.
It was a singleton, dead in the water. I could lock onto it, and target it, but I couldn't get the TDC to accept the information. When I went to F6 to check out the run times, I was surprised to discover that, regardless of being locked onto the ship it wasn't showing any run time at all. I shrugged, figuring it must just be a slight glitch, and fired anyway. I fired twice, and both times they angled off into oblivion, absolutely not even
close to where I was aiming and locked onto.
It wasn't until I manually targeted and entered the information that I generated a hit.
