ZBrushCentral

lost subtool history

Hello,
So I wanted to make a timelapse of a sculpt i did a few months back but when I opened the .ztl and it no longer has any history… I have several versions of the .ztl but it seems none of them have any history.
Is it gone gone>? and way to recover?
Thanks

ZTL doesn’t saving the undo history, for that you have to save Zproject (ZPR).
So, no.