Here is a fourth beta test for Teensyduino 1.59.
Arduino 2.0.x, all systems platforms:
use Boards Manager to install Teensy version 0.59.4
(to refresh versions, Shift-Ctrl-P and click "Arduino: Update Package Index")
Arduino 1.8.x, Linux 32...
followups on this thread:
https://forum.pjrc.com/index.php?threads/issue-with-audioanalyzerms-and-audioanalyzefft1024-staying-at-0-after-a-certain-period-of-time.73856/