At any given moment a battery is either "Net Charging" or "Net Discharging". Lithionics Battery Monitor app reports the Net Current at the battery terminals, where red color Current value means net discharging and green color Current value with "+" sign means net charging.
What is Net Charging? Term "Net" simply refers to prevalent direction of all combined electrical currents in the system. For example, if your solar charger is producing +30A, but your combined loads at the moment consume 100A, then you have a net discharge current of 70A. Even though your battery is discharging at this moment, all your solar power is being put to good use to offset your loads and slow down the rate of discharge.
If you want your solar power to charge your battery, then you have to reduce your loads to allow for net charging.
Another reason for your battery not charging is when your battery is already fully charged and is currently in the Float stage, which means your solar power is feeding into your loads, but not into the battery. Charge voltage is reduced during Float stage, so you might see lower voltage and smaller current showing up in your Lithionics app when battery is fully charged or was recently fully charged and is currently above 95% SOC.