Incomplete output from Python command in a Bash script

It is my first post here.

I am creating a simple bash script which should run a python command and mail the output. However, every time the script is running via cron, half of the python output is missing. Whereas, if I run the same script manually on shell, everything works as expected.

The bash script is:

#!/usr/local/bin/python3echo $(/usr/local/bin/python3 /home/tech2/myscript_v3_4-3.py -rs) > /home/tech2/weeklyreportoutput.txtsleep 180echo "Data Generated on $(date +%T_%d_%m_%y)" | mail -s "Data for Weekly SYNC $(date +%A_%F_%T)" -a /home/tech2/weeklyreportoutput.txt tech2@example.com

Note: The python script runs max for 10 seconds and output is not more than 100 lines. I have also tried without echo, but in that case python doesn't run with -rs argument.

Any help would be really appreciated.