LACP may intermittently stop distributing when master VAP is overloaded.
When the master VAP is under high load, the exchange of LACP control messages with the neighbor switch may be delayed. This happens more likely when LACP is configured for fast updates and the control packets are sent every second. The normal rate at which LACP packets are sent is 30 seconds.
The current frequency (Slow or Fast) can be verified using the CLI command show veth-stats:
The LACP frequency isn't configurable on X-series. Please change the frequency on the neighbor switch to allow slow LACP updates. See your switch documentation for information how to change the frequency. On Cisco devices, the command is lacp rate normal in the interface context.