Good day, first what kind of medium are you using? Have you had a chance to check the run off PH?
IMHO it does look like a calcium issue. Whenever I run into issues such as yours the first thing I do is check run off PH to make sure it's not a lock out due to PH fluctuations, then I go through the process of finding out what's "not" wrong with any particular plant.
CHEERS!!!