Thank you for your post.
From your description, it is difficult to determine the cause of the problem.
Are you importing an Excel file directly? If so, export to a CSV or TSV text file. Then, import the text file and see if the information looks correct. If not, open the text file using a text editor or word processor and see if you notice anything strange about the data.
Try changing the formatting of the field to display 24-hour. Does that work?
Any other information you can provide may be helpful.
TSGal, you are my hero!
I had been importing exclusively from excel, with fields in both excel and filemaker formatted in various ways.
Saving the excel file as a csv seems to have fixed the problem in its entirety. On finding this, I recognize that the files I'd imported in the past, which used 24-hr dates, were imported from csvs.
Thank you for rescuing me!!!
The timestamp format in .csv must exactly match that set in FileMaker, here: