Outside of capability scope
I’ve seen so many projects fail because they were outside of the capabilities (technical, structure, team composition, knowledge, manpower) of the executing team.
Far too often project managers (if they had any say in the bidding process) failed to determine whether the specification was within the capabilities of the team.
Determining beforehand if the team on-hand and any projected new hires matches up with the requirements and specification goes a long way to knowing whether to not bid or stop your bid on the project and shutting down any proposal effort being expended.
In common parlance, if you don’t think you can pull it off, don’t bid on it.