menu not showing on second monitor

I am using a LG 27" (27UD69P) monitor (3840x2160) mirroring my 2017 15" MacBook Pro running Big Sur 11.2.3. I am using a HP 21" (2159S) as my second monitor (1920x1080) set as an extended desktop. The menu is not showing on the second monitor. If I click my mouse at the top of the screen, the menu items will pop up. I searched for an answer and called Apple. The technician exhausted her knowledge level and referred me to a second level technician to no avail. I am thinking a resolution issue but I have not been able to fix it. Both monitors are set to their default display resolution. My graphics card is a Radeon Pro 560 4 GB, Intel HD Graphics 630 1536 MB. Any ideas how to fix this issue? Not exactly a low end MacBook Pro in 2017. Thank you!