x/tools/gopls: variable in third party package is not highlighted

[normal-cock]

What version of Go are you using (go version)?

$ go version
go version go1.14 darwin/amd64

$ gopls version
golang.org/x/tools/gopls v0.6.0
    golang.org/x/tools/gopls@v0.6.1 h1:vD171EDBkyUVyp9B45IYXklV/VEfbHgX0FKw0Q0dO30=

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"

What did you do?

nothing

What did you expect to see?

Code in my package:

What did you see instead?

Code in third party package:

Gopls(server) logs when I move cursor in format variable:

[Trace - 16:51:31.825 PM] Received notification 'window/logMessage'.
Params: {"type":3,"message":"2021/01/05 16:51:31 background refresh finished after 26.412396992s\n"}


[Info  - 4:51:31 PM] 2021/01/05 16:51:31 background refresh finished after 26.412396992s

[Trace - 16:51:35.547 PM] Sending request 'textDocument/hover - (26)'.
Params: {"textDocument":{"uri":"file:///~/.gvm/gos/go1.14/src/fmt/print.go"},"position":{"line":216,"character":15}}


[Trace - 16:51:35.548 PM] Received response 'textDocument/hover - (26)' in 0ms.
Result: {"contents":{"kind":"markdown","value":"```go\nvar format string\n```"},"range":{"start":{"line":216,"character":13},"end":{"line":216,"character":19}}}


[Trace - 16:51:35.749 PM] Sending request 'textDocument/hover - (27)'.
Params: {"textDocument":{"uri":"file:///~/.gvm/gos/go1.14/src/fmt/print.go"},"position":{"line":216,"character":14}}


[Trace - 16:51:35.749 PM] Received response 'textDocument/hover - (27)' in 0ms.
Result: {"contents":{"kind":"markdown","value":"```go\nvar format string\n```"},"range":{"start":{"line":216,"character":13},"end":{"line":216,"character":19}}}


[Trace - 16:51:35.887 PM] Sending request 'textDocument/documentHighlight - (28)'.
Params: {"textDocument":{"uri":"file:///~/.gvm/gos/go1.14/src/fmt/print.go"},"position":{"line":216,"character":15}}


[Trace - 16:51:35.888 PM] Received response 'textDocument/documentHighlight - (28)' in 0ms.
Result: [{"range":{"start":{"line":216,"character":13},"end":{"line":216,"character":19}},"kind":1}]


[Trace - 16:51:36.122 PM] Sending request 'textDocument/codeAction - (29)'.
Params: {"textDocument":{"uri":"file:///~/.gvm/gos/go1.14/src/fmt/print.go"},"range":{"start":{"line":216,"character":15},"end":{"line":216,"character":15}},"context":{"diagnostics":[]}}


[Trace - 16:51:36.126 PM] Received response 'textDocument/codeAction - (29)' in 4ms.
Result: null