LOR from non-professional employer?

[JMLS232]

I am currently a senior architecture student at a prominent public university and I am applying for graduate school. One problem I have run into, like many others, is a lack of quality recommenders. So far, I have two professors who are more than willing to write a LOR for me but, I can not think of a single other professor who knows me well enough to write a strong LOR for me. I am usually a fairly high-performing yet, low-profile student unless I pretty much forced to speak with my professors one-on-one. Also, I was unable to obtain an internship this summer because of the current pandemic so I have zero professional experience. However, I have worked for a well-known store chain since high school and all of my managers adore me. I am sure they would speak very highly about my personality, work ethic, and (ironically) my people skills. Would it be tacky for me to include a LOR from one of my managers since it is, after all, just a convenience store or could their high opinion of me and unique perspective be enough to excuse the fact that they aren't an academic source?

[Crucial BBQ]

I have been associated with higher education in the U.S. in one way or another for a decade and it is in my experience that no professor (or anyone, really) who agrees to write an LOR does so with the intention of written a bad LOR.  If they feel they cannot recommend you for any reason they will simply decline.  If a potential letter-writer does not remember you, or does not remember you well, it is common for them to ask for additional information from you to help them write their letter.  

Grad school is about doing research.  Ironically, your work ethic has nothing to do with that as it says nothing inherent about your ability to do research let alone if you actually like doing research. People skills also ranks fairly low.  

I would look at your program(s), or if in doubt, call the program coordinator and ask.  From my experiences it is okay to have at least one LOR from a non-academic source.  However, those sources should still be able to speak on your potential ability to do research.  

I suggest that you contact past professors first before using one of your managers.  However, if one of your managers has also attended grad school that could be a plus.  

[RyanS]

Letters of recommendation are also used to evaluate professionalism, not just attest to your ability to research or likelihood of succeeding in the program.  While your managers are able to speak to that, it is still better to get an academic recommendation.