the error of calculate "Gene concordance factor" using IQ-TREE

[XiangChuanyuxcy]

Dear developers：
When I use IQ-TREE to calculate the "Gene concordance factor (gCF)" of amino acid phylogenetic tree reconstructed by PhyloBayes , the following error occurs. I don't know the reason for this error, so it is difficult to solve.

Reading tree TAAPB ...
rooted tree with 55 taxa and 108 branches
Reading tree(s) file loci.treefile ...
2 tree(s) loaded (0 rooted and 2 unrooted)
Computing gene concordance factor...
ERROR: mtree.cpp:2306: void MTree::extractQuadSubtrees(std::vector<Split>&, BranchVector&, Node, Node*): Assertion `node->degree() == 3 && (it)->node->degree()
== 3' failed.
ERROR: STACK TRACE FOR DEBUGGING:
ERROR:
ERROR: *** IQ-TREE CRASHES WITH SIGNAL ABORTED
ERROR: *** For bug report please send to developers:
ERROR: *** Log file: gcf.log
ERROR: *** Alignment files (if possible)*

Thank you for your help
Best wishes!