Where are you able to get Milorganite in Canada?

Oh ok, wasn't sure if you somehow knew of somewhere that carried it in Ontario.

With regards to your grass problem. It does look like there was something placed on top of the lawn in that area. But you say there wasn't anything there so we can rule that out. Does all the grass pull up in the area that is of concern, or is there some grass in the area that is more rooted in? In the pics I can almost see some creeping bent grass. Is there any chance that grassy weed could be mixed in? Creeping bent is usually very easy to pull out. If not creeping bent, I would have to guess it's a drainage issue. Is the soil in that area extra tuff? When you water does the water run off the soil in that area and not get to the grasses roots? If that's the case I'd be tempted to core areate that area and see if it helps. You can buy a hand held areator from most big box stores and there fairly cheap if you don't want to rent a gas powered machine.

Did you check for grubs?

I have a similar issue and in my case it's party creeping bentgrass and mostly poa trivialis.

I think John is right. If you look at your pics, it has some very high density grass growing that is not typical of your desirable cool season grass. Creeping bentgrass and poa triv are both highly stoloniferous grasses that are easy to pull up when left to grow long. It looks like that rectangle section is affected but also down below in the pic also.