Is the field set as a global field and the the file hosted on a FileMaker server? If so, it will always be empty when the file opens.
If this is the case then try creating a table/field and record to hold the values for the Global field(s). Have the on open script for the file go to a layout based on the stored values and use set field to fill the global container.
Other option/simple, download the file from the server. Open the local file and put the .tiff into the global container field. Then put the file back on the server.
Adding to what Bruce has said, it does sound like a hosted file/global field issue. Note:
1. A global field in a hosted file will default to whatever data it held when it was last closed in an unhosted state. So one option is to take the file off the Server, add your file to the container field, then rehost it. However, this is (1) a major pain as a means of adding new global dat, and (2) unreliable for a host (excuse the pun) of reasons. So …
2. What Bruce suggests is the best practice way to deal with this: put all your globals in a single table; create a matching set of regular fields to the global fields you want to use; create a single record and fill each of the regular fields with whatever content you require; create a script that runs whenever the file is opened, to "prime" each global field by filling it with its matching contents from the regular, stored field.
Thanks all, that solved the issue. I took it offline added the picture and re-hosted it on the server and it stayed.