For categorized budgets, it is essential to include filters, such as the owner ID to ensure that conditions are evaluated accurately.
The issue may be occurring because in the condition section for the budget policy, some blocks included an owner ID, for example, while others did not. Alerts were triggered only for the accounts where the owner ID was specified. For example, see below:
Condition when alert would fire successfully (owner id is mentioned) -
Condition when alert did not fire (no mention of owner id in condition) -