Formulas in cells are treated as text. The leading = is not signalling formula. Seeing this in version 7.3.4.2. Worked in 7.2 and earlier.
Have you followed the instructions?, https://help.libreoffice.org/latest/en-US/text/scalc/guide/csv_formula.html?DbPAR=CALC#bm_id3153726 If so, please attach a sample file.
Created attachment 181105 [details] Test CSV I confirm the change from 7.3 with the simple test CSV. Seems regression.
Meh, this seems like NotABug because of new option "Evaluate Formulas". Please confirm that using it solves your issue.