Phoeni infantry from Carthage fold to cavalry because they drop their spears

Was this just a weird bug or am I doing something wrong? For context, always playing on very hard.

Way back in the day I did a greek campaign, and as long as morale held, the phalanx was mighty indeed. I was expecting somethine similair from phoeni infantry but boy have they been a let down in city combat so far.

Now all who have played Carthage now their initial infantry hate the pink pyjama crown for worst infantry, but I thought Phoeni infantry would counter cavalry. So far the do not. I can have a steady line but if a Scipi general decides to charge, we kill hardly any, drop spears and resort to swords. Is the armor value of the romans just too high for bronze forged Phoeni was this a weird fluke?

Of my 5 phoeni infantry only 1 managed to hold formation on the battle for Capua, (vs a principes unit) all others resorted to swords. This was the unit that fought on the plaza, all others tried to block a small street. I had to bail with 75% losses.

Earlier the same drop spears behavior happened when taking Tarentum but their I assumed I caused it by clipping multiple units inside each other. Not so this time. Luckily we 'won' that battle in the field before starting the siege so I was not punished for this behavior.

I am playing on classic with large units for context.