Diurnal tides certainly exist. They also can phase in and out of semi-diurnal cycles, since they are interference patterns. If you look at the current (Oct 11-18, 2019) weekly tide chart for Port Fourchon, Louisiana, you will see that this weekend the sea is in a semi-diurnal cycle, but by Monday it will be in a diurnal cycle. Most of the time the location only has one high tide per day.
Generally the diurnal tides in the Gulf of Mexico are prevalent on the north end of the basin, and not so much on the west coast of Florida as in the Clearwater example given, which always has semi-diurnal tides.
If you want to see very odd tides, check out Port Saint Joe, in FL, which is "in the corner" of the Gulf and therefore can have anywhere between 2 to 8 tides per day. Granted, the tides are very small, sometimes a matter of an inch difference! But the location gets a mix of diurnal and semi-diurnal mechanisms.
Cheers
RS