I think the die's not low enough in the press.
Backing out a die 1/4 turn from shell holder contact moves it about .018". When a case is all the way up into that die so set, the die's bottom will be a few more thousandths away from the shell holder due to the press flexing or springing up from pressure. And the case neck won't go all the way up into the die's neck. That's what I think is happening.
Most full length sizing dies are best set when they're backed up about 1/16 turn or .004" to .005" above shell holder contact. One can use feeler gauges to measure this.
To be sure full length sizing dies are set best for long case life and best accuracy, they should set the fired case shoulder back no more than .002". The best way to tell is using a case headspace gauge such as the Hornady LNL or RCBS Precision Mic. These gauges measure the case head to shoulder distance.
Die threads are 14 per inch. One full turn moves the die about .072"
Here's a link to something that'll help you adjust die height in the press: