We have a number of historical classic team sites running in SharePoint Online which we are now creating new modern site pages and step by step plan to convert existing pages (in root site and all sub sites).
NOTE: We don't use the Publishing feature only site pages with web parts!
Problem we face is that we have Quick Launch menu disabled following the support article Customize the navigation on your SharePoint site and the steps found in the section Turn the left-hand menu on or off for a SharePoint Online team site.
Unfortunately it doesn't seems to take effect in our combination of a Classic Team site with modern pages (we don't plan to connect an Office 365 group unless this solves the issue). Is this a known limitation and are there any features we need to activate to get the same behavior as a Modern Team Site were the Quick Launch is hidden correctly?
We have not done any master page customization, enabled any special features. we are just using OTB Classic Teams sites for long time and now like to move to Modern pages WITHOUT left navigation visible.