screenshots – sometimes file-explorer, sometimes URL

[eNGiNe]

When I want to attach a screenshot to a post, something I always and only do from my work PC on the corporate network, the next step varies for no discernable reason: sometimes I can just select a file from my drives, sometimes I'm asked for a URL. Policies mean I can't get to any external repository (such as Dropbox), so at least half the time I can't actually ask my question.

Is there a way I can be sure of getting the "upload local file" dialog?

Thanks in advance.