Google Ads blocked editing Target ROAS while promotion mode was active

Advertisers found that Google Ads will not let them edit Target ROAS while promotion mode is active on the account. The interface says "You can't edit your Target ROAS while promotion mode is active" and offers ROAS tolerance as the only lever instead.

• The blocking message: "You can't edit your Target ROAS while promotion mode is active."
• The offered alternative is editing ROAS tolerance rather than the target itself.
• Google has published no documentation explaining promotion mode or the reason for the restriction.
• Spotted by Arpan Banerjee, shared by Adrian Dekker on LinkedIn.
• If you run promotions through this mode, plan target changes before you turn it on, because you will not be able to make them while it is running.