Question: External hard drive stopped accepting large files
My partitioned external hard drive has recently stopped accepting large files. The partition I use for storing files is MS-DOS FAT32 format. I am aware of the file limit and I have successfully transferred and saved large files just below the limit in the past without issue. For example, it currently holds 4.21GB and 3.59GB video files as well as many other similarly sized and smaller files. However, it now won't let me save a 2.2GB file because it says the file is too large for the format! It successfully lets me transfer a 2.07GB file. It seems to be suddenly acting like it is an MS-DOS FAT16 format, but Disk Utility confirms that the partition is still MS-DOS FAT32 (not that I had really expected it to have just changed itself on a whim or for that to even be possible) and there is still 414.86GB of free space remaining. Running First Aid did not flag anything. I would really like to avoid having to reformat as I do not want to lose the data that already saved.
I use an Early 2015 MacBook Pro, processor 3.1GHz InterlCore i7, memory 16GB 1867 MHz DDR3, storage capacity 121.12GB running High Sierra version 10.13.1 and external hard drive 4TB LaCie Porsche Design Desktop Drive partitioned 2.48TB Mac OS Extended (Journaled) for backups and 1.52TB MS-DOS FAT32 for storing files, 1.11TB used and 414.86GB free.
I would be very grateful for any advice about why this has happened and how it can be resolved.
MacBook Pro (Retina, 13-inch,Early 2015), macOS High Sierra (10.13.1)