You need to do two things to resolve this.
First, click on the repeater and uncheck the ‘Fit content to HTML’ checkbox in the Style tab. This means that the repeater will size itself to what is visible when the row loads, but won’t update the size if what is visible changes.
Next, when you show your menu, click the ‘More options’ link in the Show/Hide interaction you use for the menu and check the ‘Bring to front’ checkbox. This will show the menu and place it above the repeater row, meaning it will display even if it is not visible inside the repeater row.
table-w-submenu-amended.rp (58.1 KB)
Note - if you need to combine this kind of menu with a repeater row that has different open/closed states, you can fudge it by placing the context menu above the row rather than below it - this doesn’t trigger a resize, meaning you can leave the ‘Fit to content in HTML’ option checked and it will still work.