Awakened Added Fire Damage Support does not apply +1 to Supported Physical Skill Gem

Awakened Added Fire Damage Support is supposed to grant “+1 to Level of Supported Physical Skill Gems” starting at gem level 5.
However, when its level is modified through gear—specifically using archdemon Crown (-2 to support gem level requirements) and Venarius' Astrolabe (+3 to gem level)—the support gem reaches effective level 6, but the +1 level to supported physical skill gems is not applied.

Just found a bug report from months ago, confirming still not fixed.
Bug Report ID: #2 375 642 755