Constantly (but randomly) getting synchronization errors when accessing ChartData.Workbook - excel

Question

I'm writing a PowerPoint macro to update chart labels. Even though I found a correct algorithm and implemented it I still get two errors when accessing ChartData.Workbook. Code:
Public Sub EnterNewChLabsNumsCats( _
objChartData As ChartData, _
objCategoriesColl As CategoryCollection, _
dctExceptions As Dictionary)
Dim objCategory As ChartCategory
Dim i As Long
Dim strCategory As String
For i = 1 To objCategoriesColl.Count
Set objCategory = objCategoriesColl(i)
strCategory = objCategory.Name
'strAnyDigit - regex for detecting numbers inside a string
If strCategory Like strAnyDigit Then
Dim strArrCategory() As String
'strArrCleaned - function to clean non-printables from the string and divide it into array
strArrCategory() = strArrCleaned(strCategory, True, False)
If (Not Not strArrCategory()) <> 0 Then
Dim varI As Variant
For Each varI In strArrCategory()
'blnInDct - function to detect if a piece of the string is in a dictionary containing expressions not to change
If varI Like strAnyDigit And Not blnInDct(dctExceptions, CStr(varI)) Then
Dim strBefVarI As String
strBefVarI = CStr(varI)
Dim strAftVarI As String
'function to change the piece of the string - precisely a number
strAftVarI = ChangeFinalNumbersTextStrOnly(CStr(varI))
If strAftVarI <> strBefVarI Then
'this is where I get run-time error '-1328086627 (b0d7019d)': Method 'Activate' of object 'ChartData' failed
objChartData.Activate
'should I use Excel.Workbook? PowerPoint.ChartData.Workbook doesn't exist
Dim objChWkbk As Workbook
If objChWkbk Is Nothing Then Set objChWkbk = objChartData.Workbook
Dim objChWksh As Worksheet
Dim objChWkshRange As Range
With objChWkbk
'this is where I get run-time error '462': The remote server machine does not exist or is unavailable
.Application.WindowState = xlMinimized
.Application.ScreenUpdating = False
If objChWksh Is Nothing Then Set objChWksh = objChWkbk.Worksheets(1)
If objChWkshRange Is Nothing Then Set objChWkshRange = objChWksh.Cells
objChWkshRange.Replace strBefVarI, strAftVarI, xlPart, MatchCase:=False
.Close savechanges:=True
End With
End If
End If
Next varI
End If
End If
Next i
'opening ChartData.Workbook again because sometimes changes are not visible on a slide
Call UpdateCharts(objChartData)
If Not objChWkbk Is Nothing Then objChWkbk.Close savechanges:=True
Set objCategory = Nothing
Set objChWkshRange = Nothing
Set objChWksh = Nothing
Set objChWkbk = Nothing
End Sub
Interestingly, I get this errors totally randomly - there's no rule when it happens because often this code works smoothly. What possibly causes these problems and how to avoid them?* Is it an effect of a turned on 'Microsoft Excel 16.0 Object Library' (which I need in this macro)?
*I managed to do this using booleans and Do-Loop While structure but I doubt it's the only way.