An investigation announced eight months ago into the behaviour of Neil McEvoy is taking longer than hoped, Plaid Cymru has admitted.
In March an internal inquiry was launched after a tribunal found the AM made a comment to a council officer that amounted to "bullying behaviour".
The inquiry is yet to conclude.
A spokeswoman said the delay has caused "understandable frustration", but claimed measures were in place to deal with complaints "more quickly".
Six months later Plaid's disciplinary panel, chaired by solicitor Fflur Jones, met to discuss whether there was any basis to further investigate three complaints submitted.
Days later the party's group in the assembly suspended Mr McEvoy. He is appealing the decision.
The Plaid Cymru spokeswoman said: "This process has taken longer than we had hoped and this has caused understandable frustration.
"The infrastructure is now in place to deal with complaints more quickly and we are committed to a swift resolution.
"However, as the inquiry is ongoing we cannot make any further comment at this time."
In September, Mr McEvoy claimed there was a "campaign to try to damage my reputation by the establishment".
"I won't take any untrue allegations lying down," he said.