Answer 1

This occurs for example when you have created a second account and you switched to that account on your device. I suppose that sololearn registers your IP-address and prevents users from likestorming their own other profiles or postings.

Answer 2

Bedřich Bukač it is more a glitch in the system as people with multiple accounts often upvote their own material ( wrongly but they do as their multiple accounts are not suppose to interact ). On more than one occasion I have liked hundreds of codes and seen the same thing... Sometimes taking as many as 6 to 7 times before finally acknowledging the upvote...