Version 3.0.2
The green circle appears sometimes. Other times it synchronizes indefinitely.
Update Electrum to the latest version on ELECTRUM.ORG (only legit website!).
Versions older than 3.3 dont synchronize anymore and have several issues (including a phishing attack that shows fake update messages and lead to fake websites). Optionally (but highly recommended) verify the file signature.
Remember to ALWAYS only use ELECTRUM.ORG regardless of the message you see.