Hey Bobfather,
please copy all the ".sc" and ".ootp3d" files with the same name per stadium for all stadiums that are not working to a folder, zip it, upload it to our ftp and post the name of the zip here. Here is a link to the discribtion of how todo this:
https://support.ootpdevelopments.com...p-developments
We will try to reproduce this so we can offer you a solution or fix a potential bug in ootp26.