TIFF File Metadata Randomly Broken / Thumbnails not displaying after batch editing metadata / creation date - help?

I am using Bridge (latest version confirmed) to manually update the metadata on film scans (this detail may be important) of TIFF files. I am updating the creation date (which is the date that the lab scanned the negative / date delivered to me) - to an actual capture date cross referenced to a digital version taken on my digital camera or phone. I am doing this to create an actual chronological display of several thousand film images taken over the span of months and then sent to a lab in large batches. 

I use the metadata panel in Bridge to manually input the actual date in the “Camera Data (Exif) - “Date Time Original” field. For the most part, this works. However, after updating the metadata, random images in each folder will fail to display a thumbnail, and stop showing the color space in the metadata. and shows “Untagged”. The files are all originally 8 bit sRGB TIFFS. 

 There seems to be no rhyme or reason to which images this happens to. Attempting to open the affected images in Photoshop fails, and opening them in lightroom displays a “unsupported” color mode error. 

The issue only seems to affect TIFF files, I have used this method on hundreds of JPEG scans with no issue. I also tried purging the cache with no effect. 

Any help or insight very much appreciated! I have intact backups of these files but the random nature of which images are affected means that replacing the damaged files would be very tedious and time consuming.