You may have already read this, but there's quite a bit of detail on how IC's conflict detection works here:
If properly configured for the user access model, it should not be possible to overwrite another person's changes by saving from IC (unless, of course, there's a bug which I would call critical and would address ASAP). When potential conflicts are detected, you will be told which file(s) conflicted and given the option to force your changes to overwrite, retrieve the server's version for comparison, or canceling the operation. If you choose the second option, the next deployment of that same metadata will not check for conflicts assuming you've reconciled any differences after the retrieve/compare cycle.
Let's check a few config things to see if you're set up correctly, and if not, let's get those changed and see if it helps. First, you mentioned that you've enable conflict detection for dedicated logins. I won't repeat the details from the link above, but if you have more than one person logging into this shared org with the same credentials, please change that to shared logins to ensure that the correct conflict detection strategy is used. Also, you mentioned that sometimes you save and nothing happens. Please make sure that under Validation and Deployment settings, you have enabled Override Save All action. The reason for that is also given in the link above, but basically if you want reliable deploy-on-save, you must enable that option.
If you have all of these set up as described above and you're still seeing the issue, please enable debug logging for metadata deployment as described here:
then reproduce issue, and finally send me the resulting idea.log file using
Help>Show Log in Explorer/Finder/Files. Feel free to email it to
sup...@illuminatedcloud.com if it contains private information vs. posting it here. That will show the conflict detection logic applied so we can see what might be happening.
I hope this helps. Please let me know your findings either way, and if there are things I need to investigate/address in IC, let's just gather the necessary details so I can do so.
Best regards,
Scott Wells