Number of multi/sub-object slot support?

When I test with oFusion Viewport, everything seem good, I use 15 slot of a multi/sub-object material
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However, when I export out. I try many time but It seem the limit of slot export supported for this kind of material is until 5
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So, If I do anything wrong, or the fact that the exporter now only alow 5 slot of multi subobject material

Ther should not be a limit on the number of multi materials supported, users have tested and used with more than 20 materials (including duplicated and non ordered ids)

Can you provide a scene where this issue can be reproduced?