Problem with synchronisation though by Dropbox

Hello!
I am using Joplin 2.7.15 (prod, win32) on win 10 home 64-bit and win 8.1 pro 64-bit (different computers.
I've got a problem with synchronization across these devices, namely: some pictures in png does not synchronize between win 10 and 8.1. Everything is at its place in win 8.1, but when I am opening a note on win 10 there is these kind of file name placed instead of real picture.

image

It does not concern every note, just the opposite - only small fraction is affected but this is still annoying.

What can I do about it? I will be grateful for suggestions.

up

Any errors in logs? Are these pictures that don't sync larger than others?

They are not larger.
I've found this "DevTools failed to load source map: Could not parse content for file:///C:/Users/Olek/AppData/Local/Programs/Joplin/resources/app.asar/Dialog.js.map: Unexpected end of JSON input".