I want to sum a bars' varible `propVolume` back since the one which `bar_index` I specify via input settings. It works just fine unless I give it `bar_index` of a bar, which is farer than 103 bars back. In documentation they say that that may be due to shortage of default buffer for `time` built-in variable, which is used my `bar_index` internally, they advise to call `max_bars_back` function to extend that buffer for `time` built-in, I did that, but it didn't help. Same problem persist - no more than 103 bars back in the history. Here is the snippet. Any ideas on overcoming 103 limit for history are much appreciated. Thank you!

```
//@version=5
// Declaration Statement
int MAX_BARS = 1000
indicator("Volume by Rang1e", "Volume by Range1", format = format.volume, overlay = false , max_labels_count = 500, max_bars_back = MAX_BARS)

enter code here
// Inputs 
int anchorInput = input.int(20000, "Anchor", 1, 100000, 1, "Anchor tooltip")
max_bars_back(time, MAX_BARS)
int n_bars = nz(ta.barssince(bar_index[1] == anchorInput) + 1, 1)
float propVolume = volume / 2 //Whatever...
float totalPropVolume = math.sum(propVolume[1], n_bars) 
plot(totalPropVolume, color = color.green, style = plot.style_columns)

```