Created attachment 192285 [details]
aroundboxlinesB.pptx: exaggerated direct formatting, bold still missing

It appears that the "bold" attribute which is applied to all the other labels is missing from the custom label "Monitor, troubleshoot and remediate" (and perhaps from "Provision, patch, and config"). 

It isn't so clearly seen in the original chart on page 2 of aroundboxlines.pptx (attachment #181458 [details] of bug #150176), so I exaggerated the document to highlight the problem, by making the word "troubleshoot" twice as large, and assigning the bold attribute directly to "shoot". (Since everything should be bold, assigning bold to "shoot" shouldn't cause any visual difference.)

The original (without my modifications) looked like this:
<c:dLbl>
    <c:idx val="3"/>
        <c:layout>
            <c:manualLayout>
                <c:x val="0.12321428571428623"/>
                <c:y val="-1.7731804364676709E-2"/>
            </c:manualLayout>
        </c:layout>
        <c:tx>
            <c:rich>
                <a:bodyPr/>
                <a:lstStyle/>
                <a:p>
                    <a:r>
                        <a:rPr lang="en-US" dirty="0"/>
                        <a:t>Monitor, </a:t>
                    </a:r>
                    <a:r>
                        <a:rPr lang="en-US" sz="1100" dirty="0"/>
                        <a:t>troubleshoot</a:t>
                    </a:r>
                    <a:r>
                        <a:rPr lang="en-US" dirty="0"/>
                        <a:t> and remediate, 24.8%</a:t>
                    </a:r>
                </a:p>
            </c:rich>
        </c:tx>

Charts weren't even imported in OOo 3.3, and initially only the fully automatic slices were bold, the rest being just a plain font and no direct formatting. Direct formatting started in 6.1 with
6.1 commit 790f9abeb1a1167ad5ab84c5fb855b36669c125b
Author: Szymon Kłos on Thu Jan 4 22:15:32 2018 +0100
    tdf#114821 import complex data labels in bar chart
    
and the label "Vendor and internal meetings" gained bold with
7.0 commit 296f3f8e4a5337b82fc72845662b5d5749acdf99
Author: Balazs Varga on Sun Jan 26 20:59:21 2020 +0100
    tdf#108107 OOXML chart: fix format of custom data point labels