My 3 pt. rear mount 64" snow blower does the same thing during certain wet snow conditions.
As the blower moves into the snow, the wet snow just keeps piling up in front of the blower (acts like a snow plow). Every once in awhile, when the pile gets to be a foot or more high, the snow will go through the blower. You are probably also experiencing the wet snow getting packed in around the auger. Some folks use silicon spray to pre-treat the auger and discharge chute, in an attempt to reduce wet snow from sticking and plugging up these area of the snow blower. The wet snow will blow, it's just really stubborn stuff.
Have you tried to snow blow slush yet ?
When you do end your snow blowing session, insure to clean your snow blower of all the impacted wet snow or slush.
If not, the stuff will freeze and be like hardened cement to remove, and your auger and impeller will not move.