We have similar problems with grading, and also some odd situations.
For example, one teacher failed to produce either a written assignment description or grading descriptors for a recent L3, 3 credit end of unit assignment.
Several different groups of students were set the same assignment - with verbal instructions only and just 7 days to complete the assignment - during different teaching sessions.
The teacher concerned then failed everyone who was set the assignment on one particular day saying they hadn't adhered to the assignment brief as they had all missed the same element from their written analysis.
The students all swear that their brief did not mention this missing element - and certainly their notes seem to prove it.
They have been told that they are permitted to re-submit this work including the missing element for a pass at level 3 AS LONG AS THEY DON'T TELL ANYONE ELSE what is happening.
Of course they haven't got a leg to stand on as they stand to fail a Level 3, 3 credit unit if they mention this to any other staff or lodge an official complaint.
Thankfully I am not part of this debacle, but have completely lost faith in the teacher involved as a result. (By the way, I hope that all made sense!)