Under what circumstances will a designated beneficiary receive a Form 1099-Q assuming no disbursement checks were received by the student or sent to the college during the calendar year?

The opening paragraph of Intuit's Guide to IRS Form 1099-Q: Payments from Qualified Education Programs states, "You will receive an IRS Form 1099-Q if someone has contributed money to a 529 plan or a Coverdell Education Savings Account (Coverdell ESA) and designates you as the beneficiary."

My mother opened a 529 savings account for my son 20 years ago and has been making 2-4 contributions per year ever since, but he never received any Forms 1099-Q until he requested a disbursement check be sent to his college bursar. Furthermore, he only received a Form 1099-Q in those years during which he requested at least one disbursement check be sent to either his college bursar or to himself.

Under what circumstances will a designated beneficiary receive a Form 1099-Q assuming no disbursement checks were received by the student or sent to the college during the calendar year?

Thanks!