I have been reworking some track issues on a section I had to remove for a Furnace replacement. A change was involved where I needed to hinge the 4 foot section so it could be raised in order to slide out the filter they installed and I didn’t want to tear it all out again just to change that filter. So as I was fitting my rail cut section so it would meet with the rest of the board, I refitted the flex track to that short section and what I found even with flex track, I had connectors hitting the ties non allowing the connector to slide on all the way. The section with the track cut was made out of a piece of Atlas sectional track. and I was only removing enough ties to connect it up. But it was hitting the permanent tie on the atlas piece and the tie on the flex track not allowing a good connection. Trimming did the trick. One thing that also helps on connections is to ensure the track continues straight through the rail connection and just past. Flex track tends to flex clear into the joint and sometimes it can cause derailments where you might not think it would happen. So your right it can be an issue . from Newman Atkinson