HTTP Proxy is used when checking for updates, but ignored when retrieving them

I have an HTTP Proxy defined. The FreeNAS system cannot directly access the internet. The dashboard shows updates are available. System/Update shows four packages available for update. When attempting to apply the updates, the FreeNAS system attempts to connect directly. No errors are displayed in the UI.

I was able to locate Bug #24865, but it appears to be closed without a resolution.

The proxy server shows successful requests:
1550521747.157 0 <redacted> TCP_MEM_HIT/200 847 GET http://update.ixsystems.com/FreeNAS/trains.txt - HIER_NONE/- text/plain
1550521747.184 0 <redacted> TCP_MEM_HIT/200 847 GET http://update.ixsystems.com/FreeNAS/trains.txt - HIER_NONE/- text/plain
1550521747.208 1 <redacted> TCP_MEM_HIT/200 2321 GET http://update-master.ixsystems.com/FreeNAS/FreeNAS-11.2-STABLE/LATEST - HIER_NONE/- application/octet-stream
1550521747.224 0 <redacted> TCP_MEM_HIT/200 1397 GET http://update-master.ixsystems.com/updates/ix_crl.pem - HIER_NONE/- application/x-x509-ca-cert
1550521747.257 0 <redacted> TCP_MEM_HIT/200 572 GET http://update.ixsystems.com/FreeNAS/Validators/ValidateUpdate-pcBO6C.txt - HIER_NONE/- text/plain
1550521747.304 4 <redacted> TCP_MEM_HIT/200 49824 GET http://update.ixsystems.com/FreeNAS/FreeNAS-11.2-STABLE/ChangeLog.txt - HIER_NONE/- text/plain

The firewall shows attempted direct connections:
Feb 18 15:33:11 VLAN248 Default deny rule IPv4 (1000000103) <redacted>:33635 64.71.187.3:80 TCP:S
Feb 18 15:33:08 VLAN248 Default deny rule IPv4 (1000000103) <redacted>:33635 64.71.187.3:80 TCP:S
Feb 18 15:33:05 VLAN248 Default deny rule IPv4 (1000000103) <redacted>:33635 64.71.187.3:80 TCP:S