On first user input, lesson exits to "What shall I call you?" prompt

[mmarks13]

I'm encountering a strange intermittent issue with the Building Blocks lesson in which the lesson exits to the "What shall I call you?" prompt as soon as the user inputs a value for the first question. Code example is below. Any ideas what might be causing this?

I am using R version 3.4.4 and it happens in both RStudio and the base RGui.

| Please choose a lesson, or type 0 to return to course menu.   
1: Basic Building Blocks      2: Sequences of Numbers       3: Vectors                    4: Missing Values             5: Subsetting Vectors        
6: Matrices and Data Frames   7: Logic                      8: Functions                  9: lapply and sapply         10: vapply and tapply        
11: Looking at Data           12: Simulation                13: Dates and Times             
Selection: 1    

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| In this lesson, we will explore some basic building blocks of the R programming language.  ...   

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| If at any point you'd like more information on a particular topic related to R, you can type help.start() at the prompt, which will open a menu of resources \| (either within RStudio or your default web browser, depending on your setup). Alternatively, a simple web search often yields the answer you're looking for.  
...    

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In its simplest form, R can be used as an interactive calculator. Type 5 + 7 and press Enter.  
> 5+7 
[1] 12  

| Welcome to swirl! Please sign in. If you've been here before, use the same name as you did then. If you are new, call yourself something unique.
 
What shall I call you?