SpecFlow bad parsing of feature file

SpecFlow Version:

[ ] 3.1
[ ] 3.0
[ ] 2.4
[ ] 2.3
[ ] 2.2
[ ] 2.1
[ ] 2.0
[x] 1.9

Used Test Runner

[ ] SpecFlow+Runner
[ ] MSTest
[x] NUnit
[ ] Xunit

Version number: 2.6.2.12296

Project Format of the SpecFlow project

[ ] Classic project format using packages.config
[ ] Classic project format using <PackageReference> tags
[ ] Sdk-style project format

.feature.cs files are generated using

[ ] SpecFlow.Tools.MsBuild.Generation NuGet package
[x] SpecFlowSingleFileGenerator custom tool

Visual Studio Version

[ ] VS 2019
[ ] VS 2017
[x] VS 2015

`Enable SpecFlowSingleFileGenerator Custom Tool` option in Visual Studio extension settings

[x] Enabled
[ ] Disabled

Are the latest Visual Studio updates installed?

[ ] Yes
[x] No, I use Visual Studio version 14.0.25465

.NET Framework:

[x] >= .NET 4.5
[ ] before .NET 4.5
[ ] .NET Core 2.0
[ ] .NET Core 2.1
[ ] .NET Core 2.2
[ ] .NET Core 3.0

Test Execution Method:

[ ] Visual Studio Test Explorer
[ ] TFS/VSTS/Azure DevOps – Task – PLEASE SPECIFY THE NAME OF THE TASK
[ ] Command line – PLEASE SPECIFY THE FULL COMMAND LINE

<SpecFlow> Section in app.config or content of specflow.json

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="specFlow" type="TechTalk.SpecFlow.Configuration.ConfigurationSectionHandler, TechTalk.SpecFlow" />
  </configSections>
  <specFlow>
    <!-- For additional details on SpecFlow configuration options see http://go.specflow.org/doc-config -->
  </specFlow>
</configuration>

Repro Project

https://github.com/StefanZivkovic/SpecFlow

Issue Description

After implementing 3 step bindings with advanced regex, some steps in feature file start to be unrecognized (which beginnings And, When or Then are not recognized as keywords, but simple black text). Regex:

[Given(@"Slave side is configured( with ""([0-9, ]*)"" byte block analyzer)?")]
[Then(@"Channel\s*(with "".+"")? is ""(Connected|Disconnected|Connecting|NoReply)""")]
[When(@"Channel( with "".+"")? is ""(Connected|Disconnected|Connecting|NoReply)""")]

We have different steps in feature files and we try to utilize one step binding so regex for that step binding ends with a bit advance pattern. We have capturing groups inside, but what i noticed that makes this problem is optional space before capturing group. I tried to match optional space with different patterns - \s*, \s{0,1}, {0,1}, i also tried to put space inside capturing group with removing space matching pattern before capturing group. Also, there are errors showing in output window when tracer for specflow is enabled. But tricky thing is that when i comment any of step bindings there are 4 or less errors and parser seems to behave nice when, at least that is what i noticed. When there are 6 errors (3 step bindings), then this problem occurs.

ProjectFeatureFilesTracker: Cannot detect generated test version for file: SpecFlowFeature1.feature, error: Version string portion was too short or too long.

Same thing happens in Visual Studio 2019 and SpecFlow for Visual Studio 2019

Steps to Reproduce

Details in Issue Description

SpecFlowOSS / SpecFlow.VisualStudio