Sonia G Jumbo Base issue

I am new to Fude and picked up the Sonia G Jumbo base brush in my first batch of purchases. It's amazing but it has a problem... after 2 uses with liquid foundation it goes quite hard and stiff to the point it's practically unusable. This is not happening with the Sonia G brush I use for concealer, but I obviously use significantly less concealer vs foundation. Searches here have told me that I need to wash it to fix this issue, but also that I should also only be washing 1-2 times a month. Am I missing something or doing something wrong? What would you do?