How to reproduce:
1. Open attached project "TestXY.zip"
2. In Project window, double-click on "test.compute" file and observe line 12 and 13
3. In Inspector window, click on "Show compiled code"
4. Observe line 17 and 18 of the opened window ("Compiled-test-.shader")

Expected result: at the end .x is picked
u_xlat0.x = imageLoad(outputTexture, ivec2(gl_GlobalInvocationID.xy)).x;
u_xlat0.y = imageLoad(outputTexture2, ivec2(gl_GlobalInvocationID.xy)).x;
Actual result: at the end .x and .y are picked
u_xlat0.x = imageLoad(outputTexture, ivec2(gl_GlobalInvocationID.xy)).x;
u_xlat0.y = imageLoad(outputTexture2, ivec2(gl_GlobalInvocationID.xy)).y;

Reproducible with: 2018.4.23f1, 2019.3.13f1, 2020.1.0b9, 2020.2.0a11