Yes, strobe tuners are very precise and can give you a lot of trouble until you get used to it. As far as the bass goes, try tuning it from the 12th fret E, or use the E harmonic. Sometimes tuners just can't get enough signal or vibration to give an accurate reading.
Why is a strobe tuner more accurate?
Among the most accurate tuning devices, strobe tuners work differently than regular electronic tuners. They are stroboscopes that flicker a light at the same frequency as the note. ... These can tune instruments and audio devices more accurately than most non-strobe tuners.
Are strobe tuners accurate?
Yes, the accuracy is within 0.1 cents (1/1000 of one semitone) as with all Peterson Strobe Tuners. An important thing to note is that Peterson Strobe Tuners have ultra high definition displays, so not only are they highly accurate in detecting a note but they have the ability to display that accuracy.