Every user has copy of the blockchain on their PC and the goal is that everyone is in sync or very close. Click on the Full Node tab, scroll down to see the connected Nodes/PCs. It can take some time on initial start up to collect peers, but if you're not getting peers automatically you'll have no way of getting synced.
You can check if you are synced by seeing a synced message in the top right of the wallet or on the full node tab. Additionally, the peak height should match closely to that of your peers. You can also confirm against a well-synced block explorer.
You can also try to force reload (top menu bar --> Force Reload). This may help get things syncing again after waiting 5-10 minutes. This should not affect your plotting.