Neutralizing Glycophosphate (Roundup)

We have a dog pen extension from our garage. It extends 10x16 and was poured when the garage was built. It has fence posts at the corners and elsewhere to hold the hog panels used as fence for keeping a large dog in. We no longer have a large dog.

For years we have sprayed Roundup along the edge to keep anything from growing there and looking bad. A band of decorative rock, 3 to 7 feet wide, creates a border between the concrete and yard grass. Last year I wanted to plant trumpet vines or honeysuckle using the panels as trellis. I put in five plants. They didn't thrive last fall and this spring I am not seeing any sign of them.

Does Roundup have residual effects? Do I need to neutralize the soil to balance the buildup of Roundup? What do I use?
Do I simply try planting something again and hope for the best?

Look at the RoundUp container and see if there's a phone number on it to contact the company. You could also try planting morning glory seeds (or some other vine seed) instead of plants. We've used RoundUp to kill a nasty weed that grows near our barn. It kills the plant, but any seeds in the ground germinate and we get a fresh crop in a few weeks.

Should be gone by now - water heavily to dilute if you think it isn't gone.

I say this because, I douse pasture fenceline annually (or sometimes twice annually) to keep grass off the electric fence. The grasses & weeds come back each Spring.. so that tells me the Roundup has been deactivated by time & water...

I use round up and plant the next day where I spray. Never had a problem. That said I am going to look for something else to use on my dandelions besides round up because the stuff hardly works.

Your plants may have died for a number of reasons.
Did you use rooted plants or cuttings?
Is there alot of urine/feces around the pen that would have been strong and killed them?
You have concrete nearby and some kind of rock, maybe they are leeching something that is altering the soil and making it undesirable for the plants.
Does it get full sun? I think trumpet vines like lots of sun?
Newly planted things usually need extra water and with gravel or rocks around it, may dry out faster.
Did you dig down and work in some compost or potting soil to help with drainage? If the soil is heavy there, it could rot the plants or they may have a hard time becoming established.
Did you mulch to retain moisture?
Did you plant too late in the year after temps dropped down too low at night? The plants wouldn't establish well that way and may not make the winter.
Other than that I have no idea, but maybe something here will be useful to you.