I have a strange behaviour with my MM v. 2.4.1 running on a Raspberry Pi 3.
When I start it seems to load correctly (since it shows all modules correctly), but then never updates anymore. All modules stay in their states.

The pm2 logs give some strange message

0|mm       | > magicmirror@2.4.1 start /home/pi/MagicMirror
0|mm       | > sh run-start.sh
0|mm       | npm
0|mm       |  ERR! code ELIFECYCLE
0|mm       | npm ERR! errno 1
0|mm       | npm
0|mm       |  ERR! magicmirror@2.4.1 start: `sh run-start.sh`
0|mm       | npm ERR! Exit status 1
0|mm       | npm
0|mm       |  ERR!
0|mm       | npm ERR! Failed at the magicmirror@2.4.1 start script.
0|mm       | npm ERR!
0|mm       |  This is probably not a problem with npm. There is likely additional logging output above.
0|mm       | npm ERR! A complete log of this run can be found in:
0|mm       | npm
0|mm       | ERR!     /home/pi/.npm/_logs/2018-08-24T19_20_52_299Z-debug.log
PM2        | App [mm] with id [0] and pid [23999], exited with code [1] via signal [SIGINT]
PM2        | Starting execution sequence in -fork mode- for app name:mm id:0
PM2        | App name:mm id:0 online

Although I can see the display, it seems to restart again and again.
And now it gets even more strange:
When I stop the pm2 process (pm2 stop mm) the electron window does not close.
And when I try to start the magic with the shell script manually (sh run-start.sh) it gives

run-start.sh: 4: run-start.sh: electron: not found

???
electron is obviously installed.

Does anyone have a clue?

npm v 6.4.0
node v 6.14.4