Shortman can only reflect what ASIC publishes every day, &...

Shortman can only reflect what ASIC publishes every day, & today's ASIC report shows shorts decreasing on 1 Dec to 5m from 12m on 30 Nov as per Shortman.

ASIC in turn relies upon the (mandatory) reporting to them by shorters. It is certainly not uncommon for some shorters to forget/neglect to report to ASIC, so you will occasionally see these sort of "blips". I have noticed a couple of other stocks I follow with similar dips for 1 Dec (certainly not all), so I would suggest one of the institutions/funds didn't submit their shorting figures to ASIC for 1 Dec.

Many of those dips (eg the earlier drops on that TLG Shortman chart) are reversed the next day or so when the reporting to ASIC resumes. So we'll see what ASIC/Shortman reports tomorrow for 4 Dec. If it does reverse for 4 Dec, one thing it does suggest is that one shorting mob dominated the TLG short position.