Discrepancy in output of post PAR simulation and bit file output
Check the pinout file, make sure your inputs and outputs are where you think they should be.

Check your reset signal is connected, and the right polarity

Check the input clock has a clean waveform at the right frequency.

If it's still not working and you have internal clock multipliers/dividers (DCMs/PLLs), remove them and reduce your logic to something simple with a single clock just to get things going and build it back up from there.