Tough to say for certain.

My best long-distance guess is that it has a root problem. Tip it out and look at it.

No plant will develop new stems if the plant ws a cutting with no nodes under the soil. If there are side shoots close to the soil, the plant may layer and produce new side shoots. This type of cutting will also have fewer chances of producing roots. Layer the lower stems if you can or repot the plant so that the first active node is at least at soil surface level, preferably a quarter inch under.

Thank you. It was not a cutting. It was a full in bloom plant rather large I purchased from Home Depot. Should I repot in smaller pot now that it is a smaller plant

There are important differences between coastal Savannah and inland Birmingham. Besides being overall warmer, the ocean produces breezes that moderate both day and night temperatures, making it possible to have microclimates that can somewhat approximate cloud forests. Even though I am in the middle of North Carolina, I've worked with a customer from John's Island just south of Charleston, where I've observed this effect.

Soil type is also very important, especially in a rainy climate. Drainage is important for Salvias, and raised beds help a lot, especially in flat areas subject to heavy rain, such as in Baton Rouge. I've observed gardens there also.

Before planting, observe the roots for color and smell for a pleasant earthy, not a rotting, scent. The latter represents a weak or dead root system. Also, besides light colored roots, guaraniticas should show signs of stolons. These side shoots eventually form new stems, mostly emerging at the rim of the pot. This is necessary for guaraniticas to survive.

Hopefully, there are nodes on the part of the plant that was plunged into the rooting medium. Stolons usually develop on mature plants, so their absence does not necessarily mean there are no functional nodes under the soil.

You can compensate for the absence of a working underground node by planting deeper to include the one just above ground, at least to have it at ground level. This will promote stolon formation or at least layering of side stems, which is the first step in forming a new root system.

I am far from a Salvia expert and in a different zone than you, but for many years I have grown Salvia guaranitica Black & Blue in pots since it isn't fully hardy here, and I can think of some potential issues. It looks like you have a vine that winds along your balcony railing. Is there shade from the vine or other plants or is the Salvia plant truly in full sun? Mine tends to like many hours of sun. Other problems that might be happening relate to the soil. You said that when you repotted it, it grew rapidly but then languished. The soil you used may be too fine-textured which would damage the roots by not allowing adequate drainage and oxygen, or it may have too much nitrogen which would lead to too much leafy growth at the expense of flowers (though with the yellow tone in your leaves, I think the first is more likely than the second.) IME I let the soil just dry between waterings of my B&B - I don't let it stay wet, but the leaves let me know if it needs watering. The watering bulb may be keeping the soil too wet. You may want to try this plant again with a better-draining potting soil and without the compost. Generally Home Depot soils tend to be too fine-textured and moisture retentive for optimal drainage for something like Salvia guaranitica. (I am assuming that since you bought the plant at HD, the soil may have come from there as well.)