I had a really hard time with creating a ODT invoice template, als LibO ever wanted to create formatting which would disturb creating the actual invoice.
By accident I found that using ctrl-M is very helpful there. It removes all disturbing formatting - which can be re-applied later to make the invoice look more pretty. If this finding can be confirmed to be useful by other people, I’d strongly recommend to add it to the docu esp. this page.
Fine if you like it.
My suggestion for an efficient workflow is:
copy-paste all the desired variables into place (hopefully some day there will be explanations what these variables actually do to avoid so much trial-and-error)