Hello there,
What BitLocker group policy settings did you configure for all users?
BitLocker recovery passwords are only saved to AD and AAD at the time they are set (or reset). Thus, you must either rotate them (which can be done using Intune) or send a script to them to force them to save their keys to AAD.
Here is a similar case with marked answers.
Missing Bitlocker Recovery Keys in AAD/InTune https://learn.microsoft.com/en-us/answers/questions/756891/missing-bitlocker-recovery-keys-in-aadintune.html
Bitlocker Recovery Key is not present in AD for some users https://learn.microsoft.com/en-us/answers/questions/410264/bitlocker-recovery-key-not-present-in-ad-for-some.html
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