I found out a weird thing about loading ztl.
Previously i have error opening a ztl file in Zbrush. I realized that this problem occur to me when i open this file from a mapped drive.
I tried again on the same file but this time from its proper directory. I managed to open it.
Zbrush somehow doesn’t take mapped drive as a proper link to the file?
Anyway this is how i managed to retrieve my error files:)
hope this may help