Using the verbose (layer name) option for the G’MIC filter within GIMP results in the following layer name:
[G'MIC] Inpaint [multi-scale]: -gimp_inpaint_patchmatch 0,9,10,5,1,255,0,0,255,0,0
Which is the same information which is available through the verbose log output. However this layer name is identical for the case where the mask is selected, as for the case when the mask is not selected. Therefore it does not reveal any more information which explains the different results for when the mask is selected versus when it is not selected.