In 1.12.2, oredict is in "oreDict" format, however, in 2020.1, whatever you write, the ordict will automatically become lowercase "oredict."
I confirmed this here:
Issue comments
We have released a patch update to fix this and a few other bugs:
2020.1.05113
- [Bugfix, 1.14.4] Custom dimension portals did not work
- [Bugfix, 1.14.4] Data pack pack_format was set to 1 instead of 4
- [Bugfix #56503] Vanilla advancement triggers did not work with custom blocks and items
- [Bugfix #56505, 1.14.4] Advancement name and descriptions did not work in data packs
- [Bugfix #56537, 1.14.4] Comparator item was mapped to a composter
- [Bugfix #56537, 1.12.2] Ore dictionary names were lowercased
If you have update notifications turned on in MCreator, you will be notified if you need to patch on your next launch of MCreator.
To apply the patch, redownload and reinstall MCreator 2020.1
We will fix this in next release or in a patch if we will make one.