The Polywell experiment—conducted by EMC2—is currently running at WB8–8.1, with the awarding contract details shown here.
RECOVERY-- Research Development Test Evaluation (RDT&E) Plan Plasma Fusion (Polywell) project. The Naval Air Warfare Center Weapons Division, China Lake has awarded a Cost Plus Fixed Fee contract for research, analysis,
development, and testing to validate the basic physics of the plasma fusion (polywell) concept as well as requirements to provide the Navy with data for potential applications of polywell fusion with a delivered item, wiffleball 8 (WB8) and options for a modified wiffleball 8 (WB8.1) and modified ion gun.
The progress is reported on the US contracts progress page (for all its problems, the US government makes Cameron's promises of transparency look like the obfuscating arse-wibble that it is), which reports that the project is "More than 50% Completed". So, no research continues and no massive barriers have yet been found.
It's also worth reading some of the comments at the Talk Polywell boards—a forum on which R Nabel, currently heading the EMC2 experiments, often posts.
Related posts on Polywell can be found here: Polywell reactor