Created attachment 182414 [details]
screenshot with comments

I have one Calc document open with all text = "Liberation Sans, 10pt".

Copy a cell, paste it into a new Calc document. Text appears much smaller as "Noto Sans, 7.2pt".

In this case, I was selecting certain column headers to copy into a new document to design a new layout.  So, after pasting a few column header labels, selected Row 1 and changed the font/size on the Formatting bar to "Liberation Sans, 12pt"; but the change did not change the visible text, even though the Formatting bar displayed as desired.  I have to select each cell in turn to force the desired font/size to display correctly.

When these column headers (the entire row) are set to "Liberation Sans, 12pt"; if I add another header cell, that cell is "Noto Sans, 7.2pt" and the Formatting bar font and size are blank as expected. 

Again, change the font/size of the row... Select the newly pasted cell, Formatting bar shows the desired font/size; but the _visible_ text is still "Noto Sans, 7.2pt"...

Now, with a cell displaying as "Noto Sans, 7.2pt" on a row set to "Liberation Sans, 12pt", right click on the cell and Clear Direct Formatting -- that cell is now "Liberation Sans, 10pt" (as from the source document)...

Result:
row:  "Liberation Sans, 12pt"
some cells:  "Liberation Sans, 12pt"; but displaying as "Noto Sans, 7.2pt"

Clear Direct Formatting on cell(s) displayed as "Noto Sans, 7.2pt":
- row:  font/size on Formatting bar now blank (cell(s) different from row)
- cells:  "Liberation Sans, 12pt"; some displaying as "Noto Sans, 7.2pt"
- cleared cell(s) format: "Liberation Sans, 10pt" displayed correctly

Select row, and set Formatting bar to "Liberation Sans, 12pt":
- "Liberation Sans, 10pt" cell(s) change display to "Liberation Sans, 12pt" 
- cells displaying as "Noto Sans, 7.2pt" do not change; likely due to already being "set" to "Liberation Sans, 12pt"