"Storage limit reached" even though there is plenty of free space

On an iPad, I tried to upload an mkv-file using the "Sharing via Wi-Fi"-feature, but got the "Storage limit reached"-error even though the iPad had plenty of free space. File size is 4090871641 bytes. I then retranscoded the mkv-file into two parts and was able to upload each part separately: first part size 3623173297 bytes and second part size 476012985 bytes.

VLC for IOS version: 3.3.7

Notes:

• At first I tried to split the original file into two parts like this: about 2.4 GB and 1.6 GB. The first part uploaded fine, but the second part got the "Storage limit reached"-error. I then tried making the first part bigger (as described above) and that was a success.
• A week or two ago I uploaded the same original mkv-file to another iPad using "Sharing via Wi-Fi" and there were no problems. So I guess the problem is not the file size, but some bug in free space calculation.