[2022] Frag cannon not usable

I can assign my frag cannon to a fire group, but after deploying the hardpoints, the cannon is just not visible in the HUD and cannot be fired. Other weapons are displayed properly and can be used. There are numerous reports about bugs in the fire groups, but none of the solutions (restarting the game, unequipping and then equipping the weapon again) have worked for me? Anything else I could try? Using the PC version, btw.

Edit: Thanks for the answers. As /u/Luriant has pointed out, this problem is already discussed in the issue tracker:

https://issues.frontierstore.net/issue-detail/48614

https://issues.frontierstore.net/issue-detail/48836