When you import an ISM repository into Revit the model has to regenerate after the ISM import process is finished. One of the warnings you are likely to get during the regeneration is “Beam or Brace is slightly off axis and may cause inaccuracies”.
Expand the warning in the dialog and the framing member information is listed for each of the warnings.
You can examine the frame member by using Manage > Inquiry > Select by ID on the Revit menu. Enter the unique ID shown for the framing member and click the Show button.
The member will be highlighted in the model. Open the floor plan for the level that the member is on and examine the member for proper alignment.
If you find that the member is misaligned it was probably an error in the origin application that the ISM repository was created from. Examine the framing for misalignment in the original model and fix an issues found.
Create a new ISM repository and import it into Revit.