Error when building Designspace 5 file with a discrete axis, 2 fonts (roman and italic)

When I try to build the designspace file I get the following:

```
INFO:fontTools.varLib:Merging OpenType Layout tables
fontmake: Error: In 'MyFont.designspace': Generating fonts from Designspace failed:

Couldn't merge the fonts, because the glyph order was inconsistent between
masters. This happened while performing the following operation:
GPOS.table.LookupList.Lookup[0]
```
Both fonts, roman and italic builds correctly when doing it separately, is it required that both set of sources have the same glyphorder?

This is how it looks the Dspace file, any idea what I’m doing wrong?

```

```

Start by reproducing the build from MyFont.designspace with the six named UFO sources and inspect the glyph order in the roman and italic files. Trace the fontmake/fontTools path reported in the GPOS LookupList.Lookup[0] error. Done means identifying whether the designspace setup or differing source glyph orders causes the failure, with a documented diagnosis or targeted regression coverage.

Written by the indexing model from the issue text.