Dissolve from video to still image - how?

I have a simple project with old video footage without sound and some still images in jpeg.

I've put a series of still images at the start of the sequence, then some video clips with one still image somewhere in the middle between two video clips.

I've selected (somehow, I am a newbie so I don't recall exactly how I did all of them at once) everything and added the default (dissolve) transition. That has worked everywhere except for where the video clip is followed by a still. I've found on the net that this is normal behaviour for Premiere Pro, but I haven't found a way to get around this (there must be one). For once, my video material doesn't have 'unused bits at the start and the end, the 'handles') and the explanations I have found sometimes make use of that.

So, I'm turning to the forum myself: how can I get a dissolve from a video clip to a still clip? What steps do I need to follow?

I'm using CC on a Mac.