No, I haven’t had this experience before - but there’s several things we can do to troubleshoot.
1. if you create a brand new channel with no fields, can you create and save entries in this testing channel (this is a decent half-split point and will separate the “fields” from the “channel” for troubleshooting purposes) - if it saves okay… we’re probably dealing with one of your custom fields. If it does not save okay… then it’s a problem with saving the channel entry at its most basic level.
2. are there any errors in your control panel log? (Tools => Logs => Control Panel Log)
3. If step 1 saves okay, you might then want to start adding fields to your testing channel (one at a time) - and see which one causes it to break… then we’ll have some more information to begin debugging.
Let us know what you find