Thank you for filing a gopls issue! Please take a look at the Troubleshooting guide, and make sure that you have provided all of the relevant information here.

Can you please share the output of gopls -rpc.trace -v check path/to/file.go?

Can you please share the output of gopls -rpc.trace -v check path/to/file.go?

020/02/07 13:51:07 Info:2020/02/07 13:51:07 Build info

golang.org/x/tools/gopls v0.3.1
golang.org/x/tools/gopls@v0.3.1 h1:yNTWrf4gc4Or0UecjOas5pzOa3BL0WDDyKDV4Wz5VaM=
github.com/BurntSushi/toml@v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
github.com/sergi/go-diff@v1.0.0 h1:Kpca3qRNrduNnOQeazBd0ysaKrUJiIuISHxogkT9RPQ=
golang.org/x/mod@v0.1.1-0.20191105210325-c90efee705ee h1:WG0RUwxtNT4qqaXX3DPA8zHFNm/D9xaBpxzHt1WcA/E=
golang.org/x/sync@v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
golang.org/x/tools@v0.0.0-20200204151227-34c67990bfe7 h1:hWZVyLW37WdETuLIGQMvQIhMfXXAOANmAIEAluZMy3c=
golang.org/x/xerrors@v0.0.0-20191011141410-1b5146add898 h1:/atklqdjdhuosWIl6AIbOeHJjicWYPqR9bpxqxYG2pA=
honnef.co/go/tools@v0.0.1-2019.2.3 h1:3JgtbtFHMiCmsznwGVTUWbgGov+pVqnlf1dEJTNAXeM=
mvdan.cc/xurls/v2@v2.1.0 h1:KaMb5GLhlcSX+e+qhbRJODnUUBvlw01jt4yrjFIHAuA=

Go info

go version go1.13.4 darwin/amd64

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users//Library/Caches/go-build"
GOENV="/Users//Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GONOPROXY="github.com/"
GONOSUMDB="github.com/"
GOOS="darwin"
GOPATH="/Users//go"
GOPRIVATE="github.com/"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/24/sx13x65d1xd1mlpy_z33l_r88l7m4g/T/go-build054596692=/tmp/go-build -gno-record-gcc-switches -fno-common"
2020/02/07 13:51:08 Info:2020/02/07 13:51:08 go/packages.Load
snapshot = 0
query = [./... builtin]
packages = 2

Thanks! Looks like gopls is able to type-check your package fine. Can you share the logs from when completion or hover fail? Information on how to capture logs is here: https://github.com/golang/tools/blob/master/gopls/doc/troubleshooting.md#capturing-logs. Make sure to add the -rpc.trace flag in your settings so that there is more detailed output.

Trace - 13:57:56.872 PM] Sending notification '$/cancelRequest'.
Params: {"id":17}

[Trace - 13:57:56.873 PM] Received response 'textDocument/hover - (17)' in 51ms.
Result: {}

2020/02/07 13:57:56 : context canceled
[Trace - 13:57:56.874 PM] Received notification 'window/logMessage'.
Params: {"type":1,"message":"2020/02/07 13:57:56 : context canceled"}

[Error - 1:57:56 PM] 2020/02/07 13:57:56 : context canceled
[Trace - 13:57:57.022 PM] Sending request 'textDocument/hover - (18)'.
Params: {"textDocument":{"uri":"file:///Users//go/src/github.com//internal/service/service.go"},"position":{"line":1243,"character":33}}

[Trace - 13:57:57.986 PM] Received response 'textDocument/hover - (18)' in 964ms.
Result: {}

[Trace - 13:57:57.986 PM] Received notification 'window/logMessage'.
Params: {"type":3,"message":"2020/02/07 13:57:57 go/packages.Load\n\tsnapshot = 1\n\tquery = [file=/Users//internal/service/service.go]\n\tpackages = 0"}

[Info - 1:57:57 PM] 2020/02/07 13:57:57 go/packages.Load
snapshot = 1
query = [file=/Users//go/src/github.com///internal/service/service.go]
packages = 0

I figured it out. Stray character in the go.mod file makes gopls angry even though everything is vendored