Hi Fredo... I noticed that SolidVolume still displays volume sometimes differently than other tools:

solid_volume_wrong_volume 4.5a.skp

Google Docs (drive.google.com)

Hi!

Calculation of volume is wrong in certain cases. See attached file.

solid_volume_wrong_volume.skp

Hi, I was in touch with them just recently. They are fast to reply as usual.

I contacted them last in May and they were quick to respond (as usual). Did you try the support email: support@skalp4sketchup.com?