Pitch detection algorithms "give up" after very little I'm sorry if pitch detection has become a stale topic here, but I'm really interested if anyone has any advice on this topic. I'm looking for the best pitch detection algorithm for stringed instruments, but I think this question will turn into "What else needs to be done to most accurately and reliably detect a pitch of a stringed instrument?".

So basically I applied all algorithms from https://github.com/JorenSix/TarsosDSP/tree/master/src/core/be/tarsos/dsp/pitch and they all differ, but they all have one thing in common, on any device I try, the algorithm reports -1 Hz after around a second of a string on an instrument being played. 

Basically the magnitude needs to be really high in order for the algorithm to detect anything. Now, obviously it's nothing on my part since I literally just copied the exact code and got those results. So there are obviously methods of still detecting a pitch in low magnitudes ( other applications, not sure what they use, can detect the pitch in the same situation for around 4-5 seconds which is a lot longer then these algorithms ), but I'm not sure what they are.
I'm not even talking about the fundamental being weak here, since the algorithm detects nothing. 

Am I missing something, or is it the more likely option that something else needs to be done other than just applying a PDA to a sound buffer and if so, what is/are those things?

Thanks!
You might just have the magnitude or gain on your test input signals turned down too low.  Or the threshold set too high.  Or poor microphone placement.  Or perhaps you need an AGC controlled gain block before the pitch estimation algorithms to stabilize the decay portion of any ADSR-"like" amplitude envelopes or sound evolutions.

The above assumes you have a decent S/N ratio (e.g. little background noise and no harmony or accompaniment).

Also, you use a singular "best algorithm", when multiple algorithms (plural) may more appropriate for different portions of a note's envelope, and/or different sized stringed instruments.  In addition, your list of algorithms does not include any of the newer machine learning (ML or Convolutional DNN) inference methods of pitch detection/estimation or octave resolution.  Perhaps even RNNs to use melodic history to improve prediction statistics.