Ansible errors with incorrect sudo password

This was previously working, but about a month ago, after an update, it stopped. This is for my home network. I have 3 Kubuntu computers, 1 working as a server, with Ansible installed, 2 client workstations.

THis is the error message - "fatal: [desktop1]: FAILED! => {"msg": "Incorrect sudo password"}"

I can log into all 3 computers with the same ID and same password. Once there I can run 'sudo apt-get update (or upgrade), on all 3.
I setup passwordless SSH keys on each of computers. I can ssh into the server and then ssh into each of the clients from the server.
On the server, in my home directory, I have a folder called playbooks. In it I have 3 files. 1 - update.yml, 2 - update.sh, 3 - secret.

When I run 'ansible-vault edit secret', I can see 'ansible_sudo_pass: xxxxxxx' (xxxxxx replaces my real password).

update.sh contains only 1 line: 'ansible-playbook update.yml --ask-vault-pass'. When I run this, it asks for the vault password, then shows the task names where it errors out.

update.yml contains the following lines:
---

- name: Update Apps
hosts: kubuntu

vars_files:
- secret

tasks:
- name: Update Cache
become: true
apt:
force_apt_get: yes
update_cache: yes

- name: Apt-get dist-upgrade
become: true
apt:
force_apt_get: yes
upgrade: dist
autoclean: yes
autoremove: yes

Like I said, this used to work, now I get the sudo password error. Can someone help me figure this out?