With my deep respect, I have more than 20 years of experience in the field of information security, working with SOC and CSIRT teams, and providing support to clients to ensure compliance and protection of their information within their company. I have seen that Windows does not have a monopoly on malware even though it is the primary infected platform (inevitably when you represent over 90% of the ICT population...). If indeed following the good practices mentioned in your link allows avoiding several infections, there is always a risk. A risk that I feel I should mitigate.
In the case that is mentioned, and which particularly impacts me for Microsoft Office 365 applications (Word, Excel, Powerpoint, Teams, Edge), I have a little difficulty in making the link between a protection system against the risks of malware infection of all types and the invalid signature error unless and that is perhaps if the signature control depends on a connection to an Apple server and that the protection software (firewall) would cause a connection latency not foreseen in the signature control processes.
What's more, I don't experience this problem on an older machine protected by the same solution, which also uses the same Microsoft Office 365 applications, but due to its age, only runs an older version of MacOs, the HighSierra version.
As cambsGooner mentions below "let's get a fix to this." but I'm a bit afraid due to the fact there is no reaction since the last post of March 8.
