Stephen M. Henning wrote:

Azaleas need sun to set flower buds. If your plant has too much shade,
then that could be the problem.

Sun during what part of the growing cycle? My plant is more or less
an understory planting for a huge oak tree about 30 feet away in the
yard. So, it gets several hours of full sun in early spring, while
it is leafing out and (not) blooming, and the oak hasn't leafed out
yet. But in summer, after the oak leafs out, the azalea is in
bright dappled shade most of the day, only an hour or two of full sun.