Thanks for your question.

We apologize for our tardiness in answering it. This is a very busy time of the year for us, often getting close to 40 questions per day.

Despite your efforts, I believe that your plant experienced some sunscald. I have two reasons for thinking this.

One of the first events that you experienced was leaf lost. I would guess that this occurred rather quickly. This is consistent with sunscald.

Secondly, the stem was green on its underside (protected from the sun) whereas its topside (exposed to the sun) was bleached out. This too would be expected with sunscald

See:

https://extension.umn.edu/yard-and-garden-news/gardens-get-sunburned-too

It appears that these pots might be on a deck. Might this deck be facing towards the south? Whatever the case, during the hot portions of the day move the pots to a shady location. If moving the pots becomes too laborious, consider covering your pots during the hottest parts of the day with a row cover (available at any gardening center). Or you could use what is called a shade cloth, also available at a gardening center). See the following for information on these and related points including how plants typically recover from sunscald:

https://extension.umd.edu/resource/row-covers/

https://extension.sdstate.edu/leaf-scorch-and-sunscald-garden

Consider adding a wood mulch around your plants in the pots. This will help cool the soil and absorb some of the intense UV light from the sun. Watering daily, especially in the morning, will also be necessary.

I believe your plants will recover if some of these procedures are done.

Good luck. Let us know if you have additional, related questions.