My console program output does not seem to work with grep

Question

I'd like to filter some output out from the program I wrote in python3 on my Mac.

Here is my command line:

python3 pepsr-excalibur.py -t 6000 -c 0 | grep -Ei "Module"

Nothing is out despite the presence of the requested line.

The logs I have when I don't grep:

11 mins 17 secs |#426|   ID: 18217040    X Rx                DL:  8    03 26 00 00 00 00 00  | OE.....: Smartbox  | — | 
11 mins 17 secs |#427|       ID: 0351    S Rx                DL:  8    38 02 72 03 d8 09 a8  | Victron: Cluster   | — | DVCC: CCL: 88.200A | DCL: 42.400A | CVL: 56.800V | DVL: 252.000V
11 mins 19 secs |#42b|       ID: 037a    S Rx                DL:  8    aa aa aa aa aa aa aa  | Victron: Cluster   | — | Module 0 alarms: No alarm
11 mins 19 secs |#42c|       ID: 037b    S Rx                DL:  8    00 00 00 00 00 00 00  | Victron: Cluster   | — | Module 0 identifier :