Dispute with manager

[takemetothespace]

This manager who is not my line manager has said something in front of few people that I am not doing the tasks that I should be doing .I was shocked and this was never brought up by my line manager.Then this manager said that they will be speaking to my manager .The way it was communicated, I actually felt bad .Then this manager ticked those tasks as completed when they were not actually completed.
These tasks might show up as uncompleted if they are added to my workload recently which my line manager is aware of and not this manager.
I have taken my concerns with my line manger and it has escalated further that this is not the right behaviour.while it's getting addressed: Aibu not to say hello/ hi to this manager? This manager is blanking me and I am doing the same. This environment is really uncomfortable.

it’s quite rude behaviour, this person hasn’t gone about it in a way that will get a positive outcome. It’s confrontational and hostile. Not good management.

Totally agree, I hope I'll get apology for this behaviour, but few people are saying it will be brushed under the carpet. I am new to this job. It's big company.

Yeah, blank the manager, don't even have eye contact.

This is bullying and I suggest you log it, dates, times, incident details in case you need to take it to HR or Acas.

Some ignorantly say its clash of personalities, which it is not. It is an anti-social coping mechanism and is a sign that this manager is struggling with their workload so they are making you look weaker than they feel inside.

You need to cover yourself, but try not to panic, I know its easier for me to say just keep working to the best of your ability so your colleagues and other managers back you up. This will enable you to shine, as you have risen above this induvidual who will shine like a nicely polished turd.

Keep all communications civil OP, so they can not accuse nor criticise you and you can hold your head up high.

My line manager actually said let them deal with it first before reporting formally. However I have reported to my union. Union advised that If it's not actioned then they suggested they will raise it as formal complaint.

If he’s sulking, he’s hardly likely to apologize is he? He’s waiting for you to fold.

I would still smile and say good morning every day, but no further contact unless necessary.