The Wall Street Journal had an article noting that even though Florida has had schools open all year, there hasn’t been any surge of cases in the schools or from the schools. (WSJ Article). And see this chart from Twitter, on cases in counties in Florida and whether the county had a mask requirement for schools. You can see that the unmasked counties actually tend to have the lowest case rates. As usual, you have to be careful because high case rates could lead to more masking, but it seems clear that the absence of masking in schools hasn’t led to case surges in the counties where those schools are located.
The Healthy Skeptic is a website about the health care system, and is written by Kevin Roche, who has many years of experience working in the health industry. Mr. Roche is available to assist health care companies through consulting arrangements through Roche Consulting, LLC and may be reached at 
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My theory is since most masks worn in public to a degree will break down larger droplets to smaller vapor/aerosol particles. The longer the mask is worn the more saturated it will become which will increase the quantity of the projection. While the projection distance will be reduced, suspension time in air will increase and normal air flow of the room will move the particles farther. This would apply to the source control theory failure. Most masks offer no protection from virus for the user. There are a lot of variables in data one must consider but I have seen enough charts comparing mask mandated areas and areas with no mask mandates one needs to consider the possibility masks have the potential to increase the spread whether it is a process issue or an application issue.