They're all at 3.7,Do you have a voltmeter?...If so, check the voltage of the batteries..a freshly charged cell should read maybe in the 4.17 to 4.20v range..If they are in that range then unfortunately I would suspect a faulty mod.
I left the mod on while it charged last night and it charged it up to 3 bars, it has 5 bars, imma get a chargerIf your charging via the MOD, I would recommend getting an external charger. Some MODs (possibly that one) do not charge batteries correctly.
They are decently priced (not expensive) and well worth the investment.
https://liionwholesale.com/collections/chargers
https://www.imrbatteries.com/chargers/