Phrase to describe a fix that doesn't address the underlying issue?

Solution 1:

I would call these fixes "band-aid solutions"

a temporary solution that does not deal with the cause of a problem

from Cambridge

Solution 2:

What about the idiomatic phrase, [to] "paper over the cracks"? (BE) To hide problems...in order to make a situation seem better than it really is. Cambridge Dictionary online.

Solution 3:

In the context you are using as example, I would think "stopgap" as a good fit. "Band-aid", "Finger in the dike fix" come to mind as well.

Solution 4:

Originally AmE, but now used more widely, 'quick-fix' is both a noun and adjective with wide currency:

A. n.
A quick and easy remedy or solution. Also depreciative: an expedient but temporary solution which fails to address underlying problems.

B. adj.
1. That fixes something quickly; (also) that can be fixed or made quickly; that is quick and easy to fit, prepare, etc.
2. fig. Of a measure, solution, repair, etc.: that is a quick-fix; expedient but temporary.

["quick-fix, n. and adj.". OED Online. June 2016. Oxford University Press. http://www.oed.com/view/Entry/265845?redirectedFrom=quick+fix (accessed September 02, 2016).

Recent Examples:

While engineers say improper road design, quick-fix solutions and "perpetual construction activities" are to blame for waterlogging issues, ....

(The Hindu [IN], "Green experts seek revival of natural drainage system", June 20, 2016. Emphasis mine.)

... close to 50 tool tips that provide guidance on selecting the right tool for the job, room renovation reveals, a selection of quick-fix home hacks, ....

(Scoop Business [NZ], "Mitre 10 launches online video channel", 17 August 2016. Emphasis mine.)