The Uncanny wrote...
But as someone who has been brought back from the dead maybe you wouldn't linger on the day to day of what she did for you but would instead come repeatedly to the bottom line: this woman saved my life. I'm walking, talking and breathing again because of her.
There's also those Sheps who don't want to dwell on, think about, or maybe even believe the whole resurrection spiel. Main!Shep had a bit of a crisis of faith once she finally trusted Miranda and Jacob enough to believe they weren't lying to her and she wasn't just comatose and captive; she simply doesn't allow herself to think about the fact that she was ever
actually dead, because she doesn't have the time (or, at the moment, emotional fortitude) to sit down and have the soul-shattering existential breakdown that accepting that would lead to. She doesn't look at Miranda and think, "this woman saw me as a pile of meat and tubes, this woman reconstructed my esophagus and genitalia, this woman brought me back to life," because that would mean that she's acknowledging to her conscious mind that any of that ever actually happened. What she sees when she looks at Miranda is "too smart to be as much of a Cerberus dupe as she is, too kind and idealistic to be as amoral as she is, someone to help," and some people are very attracted to that (not main!Shep, but I'm just saying it's possible).
Also, it's worth considering that Miranda may not have been that hands-on involved. She was the project director; directors are often too busy or too unqualified to do the same work they're overseeing. I got the impression running around Lazarus that Wilson was the real expert, the head of the medical group, and Miranda was the supervisor who knew enough about the process to know whether progress was being made but wasn't actually involved beyond stopping in now and then to check up (she's certainly not working the first time Shep wakes up, or she'd have just administered the sedative herself). In which case there's much less weirdness on both sides.
And she definitely does strike me as competence-sexual rather than having any real concern for gender.