The most common reason late fees aren't charging is that they haven't been turned on at the lease level. Even if a late fee policy exists at the company or property level, late fees won't apply unless enabled on the individual lease.
Other Reasons Late Fees May Not Charge
Lease, property, or company-level late fee settings are not configured correctly — check all three.
The default rent category is not set up properly. If you use a custom category for rent income, update it under Settings > Default Accounts.
The late fee policy was created or edited after rent was already posted — late fees only apply to charges posted after the policy was set up.