Strategy loses money when market creeps lower and overall IV increases the same across all expirations, which adds losses to your losing long equity portfolio. However, to your advantage, markets rarely "creep lower".
Overall strategy can also bleed money (time decay) in a range-bound market environment and calendar IV differentials flatten out from steep levels. If we stay in this range and vol continues to creep in your overall position will bleed money. If we continue to slowly rally, the IV term structure will normalize and your options position will likely lose money as your long front end IVs collapse more than your short far-out IVs, which could negate your long equity portfolio winnings.
In March, your options put calendar position probably protected you from huge losses in your long equity portfolio....not sure if you were up or down money overall on the March lows. In April, even though your long front month IVs crashed relative to your short back month IVs, your overall position benefitted from a massive rally, and your front month gamma saved you from the term structure IV collapse (calendar skew flattening).
If you sold out of your short calendar position during the crash in March, then you should be up pretty good money for the year, since your long equity position is basically a scratch for 2020.