However I have also found that certain items are low or out of stock that defy logic.
None of this defies logic. Literally makes sense to me.
No hollandaise sauce? No Bearnaise sauce and they were pretty much out of most of these types of sauce packages. And I was in the store first thing in the morning too - right after the senior hours - so are seniors buying up these sauces along with the toilet paper?
The only right answer is the supply chain/supply and demand. And senior citizens have nothing to do with it. Weird that you are forgetting a few million Millennials and older folk forced to stay at home, missing favorite brunch outings now resorting to making their own brunches whenever they please to suit their comfort eating needs. They're buying these relatively easy to cook, inexpensive items like ... retail hotcakes.
And it's easy to figure out that the companies that make these sauce packets clearly aren't making new products as they very much aren't and shouldn't be considered necessary industries to remain open and manufacturing doing this current pandemic. Thus, stores don't have any new stock coming in to replenish their shelves.
Since I shop only for myself and haven't been cooking anything more complicated or noteworthy that would use anything other than a microwave, I'm not sure if I noticed any particular unusual out of stock items that I desperately need. I've been fortunate in that way during these past few months.