In some cases that I haven't been able to determine a well-descriptive pattern for, EPPlus 3.1.3.3 seems to unformat (or at least corrupt the formatting of) certain cells on worksheets.
See the attached input and output xlsx files. The output file's Sheet1!D3 cell has been unformatted.
This is a method body snippet that suffices to reproduce the output from the input:
```
var path = @"C:\path\to\file.xlsx";
var fi = new FileInfo(path);
var ep = new ExcelPackage(fi);
ep.Save();
```
See the attached input and output xlsx files. The output file's Sheet1!D3 cell has been unformatted.
This is a method body snippet that suffices to reproduce the output from the input:
```
var path = @"C:\path\to\file.xlsx";
var fi = new FileInfo(path);
var ep = new ExcelPackage(fi);
ep.Save();
```