Can't save right dimensions of fixtures

[giusfre]

Why is not possible to save a fixture with the right dimension?
I have downloaded a Stairville Led Bar 18x3 and it is 70 x 4 x 3 cm but I want to re-save with the right dimensions that are 105 x 7 x 7 cm but it's impossible to save the new values! Somebody have this issue? Thanks

[markus]

Same here. "Beam angle" / "Type" is not changeable too. You can change the values, save, but the values in the file do not change.
See screenshot.
Please fix this bug.