Phal Philippinensis - roots drying up

[Misscd15]

Hello!

I have Phal Philippinensis with roots keep on drying up (becomes dry and yellow) and I'm not quite sure what to do about it..

I read that Phal Philippinensis likes to be bone dry between watering and doesn't like to be wet for too long, so that's what I've been trying to do, it's wet for about 2-3 days after watering and I usually water every 5 days, 4 if the weather is hot.

Can someone tell me why it's losing roots like this? and also one of its leaves is becoming very droopy and soft as well..

Thank you!!