Do players get PDGA ratings from league rounds?
Yes. Current PDGA members will earn ratings and even non-members will earn them even though they won't be able to see their official ratings until they join or renew. Players will see preview (unofficial) ratings each week when the TD posts the scores online just like regular tournaments.
If some weeks don't display preview ratings, it's likely not enough players entered that week with established ratings (propagators) over 799. At least 5 propagators are required to produce preview ratings. The good news is that once the league report is submitted to the PDGA, players will still receive official ratings for any of the weeks they couldn't see preview ratings.