Hey Kouvertier,
Thanks for clarifying. Since this seems to be isolated to 3rd party accounts, one thing you could do is to disable Notes in the third-party account settings and turn them back on. This should get them to resync to the device. Notes may be able to load them better afterward. Take a look at the steps in this article.
- "In the Settings app, tap Mail.
- Tap Accounts, then tap the email account that you want to check.
- Make sure that Notes is on."
If you're missing notes on your iPhone, iPad, or iPod touch - Apple Support
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