It seems that the number of files in loading folder has influence on the success of file loading.
Within the folder that has up to 100 files, file loading always succeed.
Within the folder that has 100-110 files, file loading succeed but progress bar is not moving while file load. Only databank counter increased.
Within the folder that has more than 110 files, file loading always failed.
I tested it on retester tab.
Malim