we have the problem, that a QC task (in this case TPC IDCs) is publishing many TCanvases during a run but only the very first object of a run can be displayed in the QCG. All following objects are shown as blank canvases. However, when one downloads the file from the QCDB, the object can be properly displayed.
The path to the objects is http://ali-qcdb-gpn.cern.ch:8083/browse/qc/TPC/MO/IDCs. There one can e.g. look at c_sides_IDC0_radialProfile.
Thank you for raising the issue and providing means to replicate!
Did you try the JSROOT platform for displaying your object?
QCG uses JSROOT behind the scenes and as far as I can tell, they have the same issue on their website. Thus, I believe it is a bug which you should raise on ROOT forum - https://root-forum.cern.ch/
Please keep in mind that they do not have access to ali-qcdb so you have to provide the root files in your post.
In order to replicate the issue, I used their supported website: Read a ROOT file