Cron not writing output to log file

I have a speedtest script that I wrote in Bash for MacOS, utilizing Ooklas Speedtest Cli utility, which executes perfectly when manually ran, but when I set my crontab it does not write to the log file in Users/Shared, although it does create the log file. I believe my cron tab is correct. I am using a third party speedtest and gsed binary not native to MacOS, could this be the issue? It almost looks like it bypasses the commands speedtest | gsed -r 's/.* ([0-9]+\.*[0-9]*).*?/\1/' and just creates the file. Does cron do something different then then manually running a script?

Any advice would be GREATLY appreciated, and I apologize for the sloppiness!

#this script runs a speedtest from a server and emails sysadmins if the download, upload, or latency
#reaches a certain threshold
#!/bin/bash

#insturctions
#install home brew; install speedtest cli; install mailutlis if necessary; configure postfix
#install gsed
#brew install gnu-sed

#debugging
#set -x


#network variables
expected_upload=5.00
expected_download=10.00
expected_latency=50.00


today=$(date +"%Y-%m-%d_%H-%M")

echo about to run speedtest

#formatting document
speedtest | gsed -r 's/.* ([0-9]+\.*[0-9]*).*?/\1/' > /Users/Shared/speedtest_logs/$today.txt

echo finished running speedtest 

echo assigning variables from results

#variables are pulled from speedtest
latency=$(awk 'FNR == 6 { print $1}' /Users/Shared/speedtest_logs/$today.txt)
download=$(awk 'FNR == 7 { print $1}' /Users/Shared/speedtest_logs/$today.txt)
upload=$(awk 'FNR == 8 { print $1}' /Users/Shared/speedtest_logs/$today.txt)

echo $HOSTNAME current upload speed is $upload
echo $HOSTNAME current download speed is $download
echo $HOSTNAME latency to the speedtest server is $latency


#determining if your download speed is lower than expected
if (( $(echo "$download < $expected_download" |bc -l) )); then
    echo download speed below expected theshold of 10 mbps - investigate
    #insert email trigger


mail -s "WARNING DEPRICATED DOWNLOAD AT $HOSTNAME" test@gmail.com <<EOF

Current download speed at $HOSTNAME is "$download"mbps

EOF

    # WHEN USING SSMTP echo -e "Subject:Depricated Download Speed\ncurrent download speed currently $download mbps"| /usr/sbin/ssmtp test@gmail.com 
else echo download speeds are normal

fi


#determining if your upload speed is lower than expected
if (( $(echo "$upload < $expected_upload" |bc -l) )); then
    echo upload speed below expected theshold of 5 mbps - investigate
    #insert email trigger

mail -s "WARNING DEPRICATED UPLOAD AT $HOSTNAME" test@gmail.com <<EOF

Current upload speed at $HOSTNAME is "$upload"mbps 

EOF


 #WHEN USING SSMTP echo -e "Subject:Depricated upload Speed\ncurrent upload speed currently $upload mbps"| /usr/sbin/ssmtp test@gmail.com 
else echo upload speeds are normal 

fi

#determining if your latency is within your defined threshold of < 50ms
if  (( $(echo "$latency > $expected_latency" |bc -l) )); then
    echo latency to speedtest server is high - investigate
    #insert email trigger

mail -s "WARNING INCREASED LATENCY AT $HOSTNAME" test@gmail.com <<EOF

Current latency for $HOSTNAME is "$latency"ms

EOF


   #WHEN USING SSMTP echo -e "Subject:High Latency\ncurrent latency $latency ms"| /usr/sbin/ssmtp test@gmail.com 
else echo latency is within the normal threshold

fi