Backups do not complete

Since about 10 days the backups do not appear to complete. They start fine, but eventually abort. I'm backing up around 150MB of data.

I believe I have changed all the settings I need to in order to complete bigger files (i.e. maximum execution times of 300 seconds and maximum memory limit of 256MB etc.). I have also tried enabling ZipArchive instead of PcIZip.

I have granted access and would be great full if you could have a look at this.