Output issue with tail + jq

[soywod]

When a custom script is piped to jq, the output seems to be discard:

echo 42 > /tmp/file

"custom/script": {
    "exec": "tail -f /tmp/file | jq -r '.'"
},

If I execute this command in my terminal I see well 42. But it does not show 42 in the bar.
If I replace the command with echo 42 | jq -r '.', it works.
If I replace the command with tail -f /tmp/file it also works.

Any clue on what's going on there?

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waybar -v: Waybar v0.9.5
uname -a: Linux workstation 5.10.11-arch1-1 SMP PREEMPT Wed, 27 Jan 2021 13:53:16 +0000 x86_64 GNU/Linux

[YerinAlexey]

You should use jq --unbuffered in this case, this way jq will print the results immediately instead of buffering them until the file (well, tail -f pipe) closes

[soywod]

Works like a charm, thanks for the help!