Try to repro

run.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+stack exec utf8-troubleshoot 2>/dev/null
+printf '\n--\n\n'
+$(stack exec -- bash -c 'command -v utf8-troubleshoot' 2>/dev/null)

stack.yaml

@@ -2,5 +2,7 @@
 #
 # SPDX-License-Identifier: MPL-2.0
 
-resolver: lts-14.25
+resolver: nightly-2020-03-10
 packages: [.]
+nix:
+  enable: true

stack.yaml.lock

@@ -6,7 +6,7 @@
 packages: []
 snapshots:
 - completed:
-    size: 524163
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/14/25.yaml
-    sha256: 97548b4e927a8a862d4a203687ca18a3f5d2ae75b4b72c946fb29c17df1a5082
-  original: lts-14.25
+    size: 501929
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/nightly/2020/3/10.yaml
+    sha256: b85b932144210a13f4628768d3e7f40bf2071ab0acf932671ff1aadac390d566
+  original: nightly-2020-03-10