How old is the battery? After 3-4 years a lot of batteries degrade noticeably on business laptops, but keep running in a reduced capacity - often for *years*. I have an E6440 with it’s original battery from 2014 (or it was replaced VERY early into it’s life since the system was purchased in 2013) and it runs fine, but at a severely reduced capacity (33%). I no longer trust the calibration accuracy in critical situations since the battery gauge has failed me before in combination to the severe capacity reduction making it hard to reliably recalibrate, but it still works. I know my time is coming, but I see no reason to change it until it gets to the point of no return especially with how hard I know it will be to get a new battery right now.
Start with a battery calibration and see if that helps. It may be too far gone as that happens with time and it can’t be avoided, but once you get to this point you have nothing to lose. I have an E6220 with a battery as well that is so tempermental I’ve had two incidents where it only charges so far (last incident was 83/100%) but it fixed itself with a recal - at the expense of a few % of remaining health (preferable to a unreliable battery gauge). If it happens again I may retire that battery before it’s too far gone due to being too untrustworthy.