We do not yet have a solution for the issue but we think that more customers will be affected thus sharing the information proactively with the partner / customer channels.. A Partner has reported to Microsoft support that multiple customer tenants are not able to toggle the "Blocked" field on an Item Card in Edit mode. The issue impacts all users who are using the iPad app version v2.7.3294. The scenario cannot be reproduced on Apple's iOS 12.1 but can reproduced on later iOS releases 12.2 and onwards).
Dynamics 365 BC support (Customer Support Service) has tested this in-house on an iPad and can confirm the behavior. The issue does not occur on browsers (in tablet mode or normal) or UWP app on Windows.
We are working on a solution as we speak and there is no need to report it again to Microsoft. As soon as the issue is mitigated, we will update this thread.