Comment 15 for bug 1525418

yes, indeed, very strange. one more possible test: a lot of the scaling in the extension is done using a bounding box calculation, which comes from a query command which can be executed in DOS.
Attached is the result of this query command on my machine. Could you check to see if yours is the same? I believe it is only the three paths that are of interest:

C:\Program Files (x86)\Inkscape>inkscape --query-all \windows\temp\perspective_extension_result.0.92.1.svg

svg8,160.69677,338.71766,266.78208,475.25519
layer1,160.69677,338.71766,266.78208,475.25519
path3680,176.19799,338.71766,224.74687,227.604
path3712,160.69677,724.90987,259.50316,89.06298
path3760,163.50219,423.213,263.97667,263.04558