OK, here are three screen shots.

First is after starting Eversync. As you can see there are 1151 bookmarks in my online account (uploaded from Chrome) and 1208 in IE's favorites folder.

The second shot is what happens when I try to download to overwrite IE's data. After I clisk "yes' to send information to developer, the process stops and exits.

The third shot shows the status after this. Note that now there are only 348 bookmarks in IE'.

I too get the pop up errors when trying to sync or overwrite local, and my bookmarks are not completed. I am running the latest 1.2.5.1 on Windows 10 1709 64bit.  Also, when I installed on a different Windows 10 system, I got pop up errors during the install. I don't seem to have any problems with Chrome or Firefox on both Windows and Mac systems.

OK, in that case 1.2.5.1 does not solve any problems for me. Trying to download favorites still get's errors and barely get half of my bookmarks. Also, trying to install on a new system also errors on the installation. Windows 10 Pro 1709 64 bit.

How do we get 1.2.5.1, when I download from your site, it's 1.2.5.0?

I am getting the same error when I try and "overwrite local". It results in an incomplete set of favorites.